» 


i 


Lida  G.  Gottseh 
346  East  Hazeltine  Avenue 
Kenmore  New  Votk 


Digitized  by  the  Internet  Archive 
in  2016 


https://archive.org/details/introductiontost21paxt 


HUMAN  ANATOMY. 


AN 

INTRODUCTION 

TO  THE 

STUDY  OF  HUMAN  ANATOMY. 

By  JAMES  PAXTON, 

MEMBER  OF  THE  ROYAL  COLLEGE  OF  SURGEONS,  HONORARY  MEMBER  OF  THE 
ASHMOLEAN  SOCIETY,  ANI)  AUTHOR  OF  NOTES  AND  ILLUSTRATIONS 
TO  FALEy’s  NATURAL  THEOLOGY. 

IN  TWO  VOLUMES,  WITH  ILLUSTRATIOA'S. 


Formative  fibres  of  the  Brain.  See  page  134. 


VOLUME  II. 

FIRST  AMERICAN  E D I T I O N , \V  I T H ADDITIONS, 

By  WINSLOW  LEWIS,  Jr.  M.  D. 

DEMONSTRATOR  OF  ANATOMY  TO  THE  MEDICAL  DEPARTMENT  OF  HARVARD 
UNIVERSITY. 


BOSTON: 

ALLEN  AND  TICK  N O R . 

18B4. 


Entered  according  to  Act  of  Congress,  in  the  year  1834, 
By  Allen  and  Ticknor, 

In  the  Clerk’s  Office  of  the  District  Court  of  Massachusetts. 


boston: 

TUTTLE  and  WEEKS,  PRINTERS, 
No.  8,  School  Street. 


CONTENTS. 


CONTINUATION  OF  ARTICLE  V.  — VASCULAR  SVSTEH. 


CHAPTER  II. 


Of  the  Veins  in  General, 

Structure  of  Veins,  .... 
General  Department  of  the  Venous  System,  . 
Veins  which  fonn  the  superior  vena  cava. 

Veins  which  give  rise  to  the  external  jugular, 

Veins  which  give  rise  to  the  internal  jugular,  . 
Veins  forming  the  subclavian  veins, 

Superior  vena  cava,  .... 

Veins  forming  the  inferior  vena  cava. 

Veins  forming  the  internal  iliac  vein,  . 

Common  iliac  veins,  . . . . 

Inferior  vena  cava,  .... 

Branches  of  the  inferior  vena  cava. 

Vertebral  sinuses  and  veins  of  the  spinal  marrow. 
Veins  of  the  heart,  . . . . . 

Coronary  Veins,  .... 

Abdominal  Department  of  the  Venous  System, 
Vena  Porta;  — Branches  of, 


Page. 

1 

2 

4 

4 

4 


7 

. 11 
13 
. 15 

15 
. 15 

16 
. 17 

18 

. 18 
19 
. 19 


VI 


COiNTENTS. 


CHAPTER  III. 

Page. 

Of  the  Capillakies,  .....  21 

ARTICLE  VI. 

ORGANS  OF  ABSORPTION. 

CHAPTER  I. 

Lymphatic  Glands,  .....  22 

Structure  of  the  Lymphatic  Vessels,  . . .24 

Lymphatic  Glands  in  General,  ....  24 

Lymphatic  Glands  in  Particular,  . . . .25 

Lymphatic  glands  of  the  inferior  extremities,  . . 25 

liymphatic  glands  of  the  pelvis,  . . . .26 

Lymphatic  glands  of  the  abdomen,  . . . 26 

Lymphatic  glands  of  the  thorax,  . . . .27 

Lymphatic  glands  of  the  superior  extremities,  . . 27 

Lymphatic  glands  of  the  head  and  neck,  . . .28 

CHAPTER  II. 

Particular  Lymphatic  Vkssels,  ....  29 

Lymphatic  Vessels  terminating  in  the  Thoracic  Duct,  29 
Lymphatic  vessels  of  the  inferior  extremities,  . . 29 

Lymphatic  vessels  of  the  perinaeum,  loins,  etc.,  . . 31 

Deep  seated  obturator,  ischiatic  and  genital  lymphatic  vessels,  31 
Lymphatics  of  the  urinary  organs,  . . . .32 

Lymphatics  of  the  parietes  of  the  pelvis  and  abdomen,  . 33 

Lymphatics  of  the  stomach  and  intestines,  . . . 34 

Lymphatics  of  the  spleen,  pancreas  and  liver,  . . 36 

The  Thoracic  Duct,  . . . . .37 

Lymphatics  which  open  directly  into  the  thoracic  liucl,  . .38 


CONTENTS. 


VH 


Page. 


Lynjphatics  of  the  lungs,  . . . . .38 

Lymphatics  of  the  diaphragm,  heart,  thymus  and  oesophagus,  39 
Lymphatics  of  the  superior  extremities,  . . .40 

Lymphatics  of  the  anterior  parietes  of  the  thorax,  . 41 

Lymphatics  of  the  posterior  region  of  the  neck  and  thorax,  41 
Lymphatics  of  the  axilla,  . . . . . 41 

Lymphatics  of  the  head  and  anterior  part  of  the  neck,  . 42 

Deep  lymphatics  of  the  head  and  neck,  ...  42 

The  office  of  the  lymphatics  and  their  glands,  . . 43 


ARTICLE  VII. 


N E K V O U S SYSTEM. 

CHAPTER  I. 

General  Divisions  of  the  Nervous  System,  . . 44 

Cerebral  Department  of  the  Nervous  System,  . . 45 

The  brain  in  general,  .....  51 

The  exterior  of  the  cerebrum,  . . . .55 

The  exterior  of  the  cerebellum,  ....  56 

The  exterior  of  the  pons  Vtirolii,  . . . .57 

The  medulla  oblongata,  .....  58 

The  medulla  spinalis,  . . . . . .60 

The  internal  organization  of  the  brain,  ...  61 

Chemical  analysis  of  the  brain,  . . . .61 

Parts  observed  in  the  lateral  ventricles,  ...  66 

The  internal  structure  of  the  cerebellum,  . . .69 


CHAPTER  II. 


The  Membranous  Envelopes  of  the  Brain,  . . 74 

The  dura  mater,  . . . . . .74 

Sinuses  of  the  dura  mater,  ....  75 

The  arachnoid  membrane,  . . . . .78 


Mil 


CONTEN'IVS. 


Tlie  pin  mater,  . . . . . ' 

Granulations  of  tlie  membrane's  of  the  brain, 

Tlie  pro])cr  membrane  of  the  spinal  marrow, 
Ligameiitum  denticulatum,  . . . . 

The  Nerves  in  General, 

Nerves  of  the  Cerebral  Department, 

Olfactory,  . . . . 

Oj)tic,  ....... 

Motores  ocolormn,  ..... 

Patlielic,  ...... 

Trifacial,  . . . . . . 

].  Opthalmic  branch, 

2.  Superior  maxillary, 

3.  Inferior  maxillary. 

Abducent,  ...... 

Facial,  ....... 

Auditory,  . . . . 

Glosso-pharyngfeal,  ..... 

Pneumo-gastric,  . . . . 

Hypoglossal,  . . . . 

Spinal  accessory,  . . . . . 

Spinal  nerves,  . 

First  pair  of  cervical,  . . . . 

Second  pair  of  cervical,  . . . . 

Third  and  fourth  pair  of  cervical. 

Cervical  plexus,  . . . .' 

Fourth,  fifth,  sixth  and  seventh  pairs  of  cervical  nerves. 
Brachial,  or  axillary  plexus,  .... 
Thoracic  branches,  .... 

Nerves  of  the  arm,  ..... 

Internal  cutaneous  nerve,  ... 

E.xternal,  or  musculo-cutaneous. 

The  median  nerve,  .... 

The  ulnar  nerve,  ..... 

Radial  nerve,  . . . . . 


Page. 

79 

80 
81 
81 
82 
8.3 

83 

84 
8.5 
86 
86 

87 

88 
88 
91 
91 
94 

94 

95 

97 

98 
100 
100 
101 
101 
101 
103 

103 

104 
104 

104 

105 

107 

108 
109 


CONTENTS. 

Circumflex  nerve,  . . . • • 

Dorsal  nerves,  ..... 
Lumbar  nerves,  . . . . • 

First  lumbar,  ..... 
Second  lumbar,  ..... 
Third  lumbar,  . . . . . 

Fourth  and  fifth  lumbar,  .... 
Lumbo-abdomhial,  or  lurrSbar  plexus, 
Musculo-cutaneous  branches, 

Genito-crural  nerve,  .... 
Crural  nerve,  ..... 
Obturator  nerve,  .... 
Luznbo-sacral  nerve,  . . . . 

Glutseal  nerve,  ..... 
Sacral  nerves,  ..... 
Sciatic  nerve,  . • . . . 

External  poplitseal  nerve,  .... 
Internal  poplitseal  nerve, 

CHAPTER  III. 

G.4NGLIONIC  Department  of  the  Nervous  System, 
Particular  Ganglia,  .... 
Ganglia  of  the  Head,  .... 

Lenticular  ganglion,  .... 
Spheno-palatine  ganglion,  .... 
Ganglia  of  the  Neck, 

Superior  cervical  ganglion. 

Middle  cervical  ganglion. 

Inferior  cervical  ganglion. 

Cardiac  nerves,  .... 

Cardiac  plexus,  or  ganglion, 

Thoracic  Ganglia,  .... 

Splanchnic  nerve,  .... 


LX 

Piige. 

110 

110 

111 

111 

112 

112 

112 

11.3 

113 

114 

114 

115 

116 

116 

116 

117 

117 

118 

120 

122 

122 

122 

122 

125 

125 

126 

126 

126 

127 

128 

128 


VOL.  IJ. 


A 


X 


CONTENTS. 


Page. 


Great  splanchnic  nerve,  .....  128 

Small  splanchnic  nerve,  .....  129 

GAr^GLi.1  or  THE  Abdosien,  .....  129 

Semilunar  ganglia  and  solar  plexus,  . . . 129 

The  lumbar  ganglia,  ......  130 

The  sacral  ganglia,  .....  131 

Hypogastric  plexus,  ......  131 

Great  Sympathetic  Nerve,  . ‘ . . . 133 

Forjiative  Fibres  of  the  Brain,  according  to  Gall  and 

Spdrzheim,  ......  134 


ARTICLE  VIII. 

PARTICULAR  ORGANS  OF  SENSATION. 

CHAPTER  I. 

The  Eye  and  its  Appendages, 

137 

Eyebrows,  ..... 

. 137 

Eyelids,  ..... 

138 

The  globe  of  the  eye  in  general. 

. 140 

The  sclerotica,  .... 

140 

The  cornea,  ..... 

. 140 

The  choroid  membrane, 

141 

The  ciliary  circle,  or  ligament. 

. 143 

The  iris,  ..... 

143 

The  retina,  ..... 

. 144 

The  aqueous  humour. 

146 

The  crystalline  lens,  .... 

. 147 

The  vitreous  humour,  . . . 

148 

CHAPTER  II. 

The  Ear  and  its  Appendages, 

150 

The  external  ear,  .... 

. 150 

Fibro-cartilage  of  the  ear,  . 

152 

CONTENTS.  xl 

Page. 

The  auditory  canal,  ......  153 

The  internal  ear,  154 

Bones  of  the  ear,  . . . . • .155 

The  labyrinth,  ......  156 

The  cochlea,  . . . . . • .157 

The  semicircular  canals,  .....  159 

Auditory  nerve,  . . . . . • 159 

Mechanism  of  hearing,  .....  160 

CHAPTER  III. 

The  Nose,  .......  163 

Mechanism  of  smell,  .....  165 

CHAPTER  IV. 

The  TopfGUE,  . . . . . . ,166 

Taste,  .......  168 

CHAPTER  V. 

The  Skin,  .......  169 

The  dermis,  ......  170 

The  rete  mucosum,  ......  171 

The  epidermis,  ......  172 

The  sense  of  touch,  ......  174 

The  Hair,  .......  175 

Organization  of  the  hair,  .....  177 

The  Nails,  .......  177 

CHAPTER  VI. 

Mdscul.ar  Sensation,  .....  178 

CHAPTER  VII. 

182 


Visceral  Sensation, 


xn 


CONTENTS 


ARTICLE  IX. 

ORGANS  OF  digestion. 

Page, 

The  Mouth,  .......  185 

The  Palate,  ......  186 

The  Pharynx,  . . . . . .187 

The  CEsophagus,  ......  188 

The  Stomach,  ......  190 

Organization  of  tlie  stomach,  ....  191 

Office  of  the  stomach,  .....  193 

The  Intestinal  Canal,  . . , . . . 193 

The  small  intestine,  .....  194 

The  duodenum,  . . . . . . 194 

The  jejunum  and  ilium,  .....  195 

The  large  intestine,  . . . . . 197 

The  Mesentery,  ......  202 

Digestion,  .......  203 

ARTICLE  X. 

organs  of  respiration. 

The  Lungs,  ......  207 

Organization  of  the  lungs,  .....  210 

Changes  which  take  place  in  Respiration,  . . 212 

The  Trachea  and  Bronchi,  ....  215 

Organization  of  the  trachea  and  bronchi,  . . 217 

ARTICLE  XI. 

organs  of  the  voice. 

The  Larynx,  .......  219 

Cartilages  of  the  larynx,  . . • • • 


CONTENTS.  Xlll 

Page. 

Thyroid  cartilage,  . ■ 219 

Cricoid  cartilage,  . . . • ■ 220 

Arytenoid  cartilages,  ...•••  221 

Epiglottis,  .■•••• 

The  ligaments  of  the  larynx,  ....  223 

The  muscles  of  the  larynx,  ....  224 

Crico-thyroideus,  ....••  224 

Crico-arytenoideus  posticus,  . ‘ . . • 225 

Crico-arytenoideus  lateralis,  . . . • • 226 

Thyro-arytenoideus,  . . • • • 226 

Arytenoideus,  . . . • • • , 227 

Mucous  membrane  of  the  larynx,  . . - 227 

The  gland  of  the  epiglottis,  .....  227 

The  arytenoid  glands,  . . . • • 228 

The  office  of  the  larynx,  .....  228 

The  thyroid  gland,  .....  229 

ARTICLE  XII. 

ORGANS  OF  SECRETION.  - 

Organs  for  the  Secretion  and  Transmission  of  Tears,  230 
The  lachrymal  gland,  .....  230 

The  caruncula  lachrymalis,  .....  231 

The  puncta  lachrymalia,  .....  231 

The  lachrymal  sac,  .....  2.32 

The  nasal  duct,  ......  232 

The  Salivary  Glands,  .....  232 

The  parotid  gland,  ......  233 

The  submaxillary  gland,  ....  234 

The  sublingual  gland,  .....  234 

The  Pancreas,  ......  235 

Organs  for  the  Secretion  and  Transmission  of  the  Bile,  236 
The  liver,  .....••  236 


XIV 


CONTENTS, 


I’age. 

Ligaments  of  llie  liver,  . , . . . 238 

Envelopes  of  the  liver,  . . . . , 239 

The  hepatic  duct,  .....  239 

The  gall  bladder,  ......  240 

Cystic  duct,  ......  240 

The  ductus  communis  choledochus,  . . . 240 

Secretion  of  bile,  ......  241 

The  Spleen,  .......  242 

Organization  of  the  spleen,  ....  243 

Office  of  the  spleen,  ......  243 

Supra-Renal  Capsules,  .....  245 

The  Kidneys,  .......  245 

Organization  of  the  kidneys,  ....  246 

The  calyces,  pelvis,  and  ureter,  ....  247 

The  Bladder,  ......  250 

The  organization  of  the  bladder,  ....  251 

The  office  of  the  kidneys  and  bladder,  . . . 252 

The  urine,  .......  253 


ARTICLE  XIII. 

ORGANS  OF  GENERATION  IN  THE  MALE. 


The  Testicles  and  their  Appendages,  . . . 255 

Envelopes  of  the  testicles,  ....  255 

The  testicles,  . ......  256 

Organization  of  the  testicle,  ....  257 

Epididymis,  .......  258 

Vas  deferens,  ......  258 

Spermatic  cord,  ......  259 

Vesiculae  seminales,  . . . . . 260 

Prostate  gland,  ......  261 

Cowper’s  glands,  ...'!.  262 

Ejaculatory  ducts,  ......  262 


CONTENTS 


XV 


Penis,  .... 
Integuments  of  the  penis  and  prepuce, 
Corpus  cavernosum. 

Organization  of  the  corpus  cavernosum. 
Urethra,  .... 
Organization  of  the  urethra,  . 

Gians  penis. 


Page. 

‘264 

264 

264 

265 

266 

267 

268 


ARTICLE  XIV. 

ORGANS  OF  GENERATION,  ETC.  IN  THE  FEMALE. 
Organs  of  Generation,  and  for  the  Nutrition  of  the 


Child,  in  the  Female,  ....  269 

Organization  of  the  Vagina,  ....  271 

The  Uterus  and  its  Appendages,  . . . . 272 

Organization  of  the  uterus,  ....  273 

The  broad  ligament,  . . . . . .276 

The  round  ligaments,  . • . . . 276 

The  Fallopian,  or  uterine  tubes,  ....  276 

The  ovaries,  ......  277 

The  gravid  uterus,  . ...  . . . 280 

Developement  of  the  ovum  in  the  uterus,  . . 282 

Membranes  which  inclose  the  Fietus,  . . . ‘283 

Liquor  Abinii,  ......  284 

The  Placenta,  ......  284 

Office  of  the  placenta,  . . . . . 287 

Funis  Umbilicalis,  ......  287 

Umbilical  Vesicle,  .....  288 

The  Mamm.e,  .......  289 

Organization  of  the  mammse,  ....  289 

Office  of  the  mammae,  .....  291 


XVI 


CONTENTS. 


ARTICLE  XV. 

THE  F CE  T U S . 

Page. 

Peculiarities  of  the  Fcetus,  ....  293 

ARTICLE  XVI. 

SEROUS  SYSTEM  AND  CELLULAR  TISSUE. 

The  Pleura  and  the  PERiTON.EUjvi,  ....  304 

Omenta,  or  Epiploa,  .....  308 

Cellular  Tissue,  &c.  ......  311 

Fat, 314 


ANATOMY 


OF 

THE  HUIMAN  BODY. 


CHAP.  II. 

OF  THE  VEINS  IN  GENERAL. 

It  has  been  already  stated,  that  it  is  the  office  of  the 
arteries  to  convey  the  blood  from  the  heart  to  the  different 
parts  of  the  body,  for  the  purpose  of  nourishing  and 
building  up  the  animal  fabric : now  there  is  a corres- 
ponding series  of  sanguineous  canals  which  return  the 
blood  from  all  the  organs,  again  to  continue  the  stream  of 
the  circulation ; these  are  the  veins.  By  the  aid  of  a 
microscope,  the  extreme  branches  of  the  arteries  may  be 
observed  communicating  with  the  minute  radicles  of  the 
venous  system,  and  transferring  their  blood  to  that  series 
of  vessels.  The  curious  and  beautiful  phenomena  of  the 
circulation  are  evident,  when  the  tail  of  a fish,  or  the  web 
of  a frog’s  foot,  is  placed  in  the  field  of  a powerful  magni- 
fier ; and  we  are  assured  of  the  fact  of  the  continuity  of 
the  two  sets  of  vessels  in  the  human  subject,  by  the 
circumstance  of  fine  injections  passing  readily  from  the 
arteries  into  the  veins. 

There  are  two  departments  of  the  venous  system  : the 
1st,  or  general  department  of  the  venous  system,  more  ex- 
tensive than  the  other,  commences  in  the  head,  trunk  and 
1 


VOL.  II. 


o 


VASCULAR  SYSTEM 


limbs,  and  transmits  the  blood  to  the  heart  by  the  venae 
cavce.  The  2d,  or  abdominal  department  of  the  venous 
sj/stem,  is  confined  to  the  cavity  of  the  abdomen,  and  is 
formed  by  the  veins  of  all  the  chylopoctic  viscera,  with  the 
exception  of  those  of  the  liver,  and  terminates  in  the  vena 
port®,  which  subdivides  and  distributes  the  blood  through 
the  liver. 

The  veins  are  far  more  numerous,  and,  considered  as  a 
whole,  they  are  much  more  capacious  than  the  arteries. 

The  distribution  of  veins  is  somewhat  similar  to  that  of 
the  arteries,  but  their  number  and  size  are  greater.  In 
general  a cellular  space,  common  to  all,  receives  both  the 
trunks  of  the  two  species  of  vessels  and  those  of  the 
nerves.  In  the  head,  limbs,  and  every  other  part,  there 
are  two  sets  of  veins ; the  superficial  and  the  deep  seated : 
the  1st  lie  immediately  under  the  skin,  or  run  above  the 
fasciae,  and  are  in  some  parts  very  large  and  numerous  and 
do  not  possess  any  corresponding  arteries.  The  2d,  or 
deep  seated  veins,  directly  attend  the  arteries.  The  union 
between  the  branches  of  the  veins  is  very  frequent ; they 
communicate  in  right  lines  or  in  arches,  and  the  smaller 
are  so  multiplied  as  to  form  complicated  meshes  of  net- 
work ; but  the  minute  ramifications  of  veins  ultimately 
form  an  inconceivable  number  of  small  canals  in  the  tissue 
of  organs,  of  such  extreme  tenuity,  as  to  render  it  impos- 
sible to  understand  their  final  distribution. 


STRUCTURE  OF  VEINS. 

The  veins  are  formed  of  only  two  membranes  ; the  outer 
is  composed  of  longitudinal  fibres,  very  easily  distinguished 
in  the  large  trunks,  and  surrounded  by  a sheath  of  cellular 
tissue,  the  layers  of  which  are  placed  very  densely  on  each 
other.  The  inner  membrane  is  thin,  smooth,  and  glossy  ; 


OF  THE  VEINS. 


3 


and  in  appearance  resembles  the  membrane  which  lines  the 
arterial  tubes,  but  it  is  more  extensible  and  less  brittle. 

Valves  are  formed  in  the  general  department  of  the 
venous  system,  but  there  are  none  in  the  system  of  the 
vena  portae,  the  umbilical  vein,  the  trunk  of  the  inferior 
cava,  in  the  veins  of  the  brain,  of  the  A^ertebrae,  of  the  spinal 
marrow,  of  the  heart,  of  the  kidneys  and  of  the  uterus. 
There  are  but  very  few  in  the  vena  azygos,  and  pulmonary 
veins.  These  valves  consist  of  a number  of  semilunar 
folds  of  the  inner  membrane  of  the  vein,  precisely  similar 
to  those  which  exist  at  the  commencement  of  the  aorta 
and  the  pulmonary  artery. 

The  valves  are  sometimes  single ; they  are,  how^ever, 
more  frequently  arranged  in  pairs,  at  other  times  there  are 
three  together.  Apparently,  their  office  is  to  support  the 
column  of  blood,  and  to  prevent  its  return  by  the  veins  from 
the  heart  to  the  surface  of  the  body ; for  the  valves  are 
pressed  close  to  the  sides  of  the  vessels  during  its  flow  to- 
wards the  heart,  but  they  are  raised  when  the  blood,  from 

is  disposed  to  pass  in  a retro- 
grade direction.  Fig.  1 re- 
presents a vein  laid  open,  thus 
shewing  the  single,  duplex 
and  triplex  valvular  appara- 
tus. 

The  veins  are  supplied  by 
very  minute  nutrient  ves- 
sels (vasa  vasorum)  and  nerA'- 
ous  filaments,  w'hich  ramify  in 
the  cellular  membrane,  and 
which  penetrating  the  venous 
tissue,  finally  terminate  in  the 
inner  surface  of  the  A'essels. 

Veins  may  be  distinguished 
from  the  arteries  by  their 
membranes  being  much  thin- 


any  accidental  circumstance. 


4 


VASCULAR  SYSTEM 


ner,  by  their  greater  number  and  size,  by  their  having  no 
pulsation,  by  the  dark  color  of  the  blood  they  contain,  and 
in  many  instances  by  the  peculiarity  of  their  numerous 
valves. 

GENERAL  DEPARTMENT  OF  THE  VENOUS  SYSTEM. 

I.  VEINS  WHICH,  BY  THEIR  UNION,  FORM  THE  EXTERNAL 
SUPERIOR  VENA  CAVA. 

Fig.  2 


I.  VEINS  VVlIICn  GIVE  RISE  TO  THE  EXTERNAL  JUGULAR  VEIN. 

The  internal  maxillary  vein  commences  in  all  the  parts 
to  which  the  artery  of  the  same  name  is  distributed  ; it  is 
consequently  composed  of  the  pterygoid,  spheno  palatine, 
alveolar,  infra-orhitar,  mental,  inferior  dental,  and  deep 


OF  THE  VEINS. 


5 


temporal  veins.  It  communicates  with  the  sinuses  of  the 
base  of  the  skull  by  means  of  small  twigs  which  pass 
through  the  foramina  of  that  region.  Upon  the  side  of 
the  neck  the  internal  maxillary  vein  frequently  communi- 
cates with  the  facial  and  pharyngeal  veins.  This  disposi- 
tion produces  the  pharyngeal  plexus. 

The  superficial  temporal  vein,  g,  commences  in  all  those 
parts  where  the  corresponding  artery  is  distributed.  It 
is  composed  of  the  middle  temporal  vein,  f,  the  anterior 
auricular  veins,  and  the  transverse  veins  of  the  face.  Thus 
formed  it  descends  before  the  ear,  and  unites  with  the  pre- 
ceding. 

The  vein  which  results  from  this  union  passes  through 
the  parotid  gland,  communicates  with  the  internal  jugular 
vein,  and  receives  the  following  : 

The  posterior  auricular  vein,  which  collects  the  blood 
from  the  mastoid  region  and  from  the  ear.  The  trunk 
then  takes  the  name  of 

The  external  jugular  vein ; it  extends  from  d to  c,  and  is 
placed  between  the  sterno-cleido-mastoideus  and  the  pla- 
tysma  rayoides  muscles.  In  its  course  along  the  neck  it 
receives  the  following ; 

The  cervical  cutaneous,  the  trachelo-scapular,  and  other 
veins  which  arise  in  the  vicinity  of  the  neck  and  shoulder. 
At  the  inferior  part  of  the  neck  the  external  jugular  opens 
near  c into  h,  the  superior  part  of  the  subclavian  vein,  a 
little  on  the  outer  side  of  a,  a,  the  internal  jugular  vein. 

2.  VEINS  WHICH  GIVE  RISE  TO  THE  INTERNAL  JUGULAR  VEIN. 

The  superior  cerebral  veins  commence  upon  the  convex 
surface  of  the  two  hemispheres  of  the  brain,  from  the 
substance  of  which  they  issue  by  a multitude  of  minute 
branches,  and  are  continued  into  the  superior  longitudinal 
and  lateral  sinuses. 


6 


VASCULAR  SYSTEM 


The  vein  of  the  corpus  strialim  is  extended  over  the 
surface  of  that  body,  and,  exactly  following  the  course  of 
the  tenia  semicircularis,  unites  with  the  following : 

The  veins  of  the  choroid  p/exws,  which  return  the  blood 
into  the  vence  galeni,  and  from  thence  into  the  right  sinus 
of  the  dura  mater. 

The  superior  cerebellar  veins  convey  the  blood  from 
the  whole  upper  surface,  and  from  the  substance  of  the 
cerebellum,  into  the  torcular  herophili  and  the  venae 

GALENI. 

The  inferior  cerebellar  veins  unite  on  each  side  of  the 
cerebellum,  and  return  their  blood  into  the  corresponding 
lateral  sinuses. 

The  lateral  and  inferior  cerebral  veins  are  very  numer- 
ous ; they  unite  on  each  side  and  leave  the  brain  to  open 
into  the  lateral  sinuses. 

The  ophthalmic  vein  commences  from  all  parts  within  the 
orbit,  and  unites  on  each  side  into  three  or  four  trunks, 
so  that  this  vein  is  formed  of  the  lachrymal,  the  central 
vein  of  the  retina,  the  infra  orbitar,  the  ciliary,  the 
ethmoidal,  the  pa/j?e6?-a/,  and  the  nasal  veins.  The  oph- 
thalmic then  passes  out  of  the  orbit,  by  the  inner  part  of 
the  sphenoidal  fissure,  and  conveys  the  blood  into  the 
cavernous  sinus. 

All  the  blood  of  the  brain  is  returned  into  the  sinuses 
of  the  dura  mater,  which  terminate  at  the  foramen  lacerum 
posterius.  This  point  is. the  commencement  of  the  jugu- 
lar vein,  and  as  it  is  here  considerably  dilated,  it  is  named 
the  sinus  of  the  internal  jugular  vein.  This  vein  advances 
a little  forwards,  and  descends  with  the  carotid  artery, 
covered  by  the  styloid  process  of  the  temporal  bone,  and 
by  the  muscles  which  are  attached  to  it.  It  communicates 
at  first  with  the  external  jugular  vein,  by  a branch  of  large 
size,  and  at  the  level  of  the  upper  part  of  the  larynx,  it 
receives  the  facial  vein. 


OF  THE  VEINS. 


7 


The  facial  vein,  e,  commences  on  the  summit  of  the 
head  and  forehead,  and  when  it  has  arrived  at  the  side  of 
the  nose,  near  the  eye,  it  has  the  name  of  the  angular  vein, 
and  receives  the  blood  from  the  ophthalmic,  ihe  palpebral 
and  the  superciliary  veins.  It  follows  the  direction  we 
observe  in  the  figure,  receiving  the  dorsal  veins  of  the  nose, 
the  superior  and  the  inferior  coronary  veins  of  the  lips, 
and  several  buccal  and  masseteric  veins.  It  is  afterwards 
augmented  by  the  ranine,  the  submental,  and  the  inferior 
palatine  veins,  and  then  becomes  united  to  the  internal 
jugular  vein. 

A little  below  the  facial  vein,  the  internal  jugular  is  aug- 
mented by  the  lingual  and  pharyngeal  veins : and  at  the 
level  with  the  superior  edge  of  the  larynx,  it  receives  the 
superior  thyroid,  the  occipital,  and  the  veins  of  the  diploe 
of  the  bones  of  the  skull. 

After  receiving  the  above  branches,  the  internal  jugular 
vein  descends  vertically  at  the  side  of  the  neck,  and  opens 
into  the  subclavian  vein. 


3.  VEINS  OF  THE  SUPERIOR  EXTREMITY  WHICH,  BY  UNITING,  FORM 
THE  SUBCLAVIAN  'VEINS,  Fig.  3. 

The  collateral  arteries  of  the  fingers,  the  radial  and 
ulnar  arteries,  and  all  their  divisions  are  each  accompanied 
by  two  venous  branches,  which  become  larger  as  they  as- 
cend toward  the  elbow  joint,  where  they  unite  so  as  after- 
wards to  constitute  two  large  trunks,  which  run  along  the 
brachial  artery  and  open  into  the  axillary  vein.  They 
receive  in  their  course  all  the  veins  which  attend  the 
divisions  of  the  artery. 

The  cephalic  vein  commences  by  a great  number  of 
branches,  disposed  in  the  form  of  a net  work,  on  the  back 
of  the  hand  and  upon  the  muscles  of  the  thumb  ; these 
unite  into  a trunk,  which  ascends  upon  the  anterior  and 


8 


VASCULAR  SYSTEM 


external  part  of  the  fore-arm,  where  it  forms  the  superficial 
radial  vein,  and  on  arriving  at  the  bend  of  the  arm  unites 
with  the  median  cephalic  vein,  which  communicates  with 
the  median  basilic. 

The  united  veins  which  form  the  trunk  of  the  cephalic 
ascend  on  the  outer  and  fore  part  of  the  arm,  then  bending 
inwards,  open  into  the  axillary  vein. 

The  basilic  vein  is  larger  than  the  cephalic,  and  is  formed 
of  three  branches,  which  are  named  from  their  situation, 
the  posterior  ulnar,  the  anterior  ulnar,  and  the  median 
basilic  veins. 


OF  THE  VEINS. 


9 


The  basilic  vein  as- 
cends on  the  inner  part 
of  the  arm  and  unites 
frequently,  as  at  e,  with 
the  cephalic  vein.  It 
then  passes  into  the  a.v- 
illa,  being  continuous 
with  the  axillary  vein. 

Fig.  3,  h,  the  axillary 
vein. 

d,  the  cephalic  vein. 
c,  the  basilic  vein. 

f,  the  radial  vein. 

g,  the  anterior  ulnar 
vein. 

The  axillary  vein  is 
therefore  the  result  of 
the  union  of  the  veins 
of  the  hand,  fore-arm 
and  arm ; it  proceeds 
obliquely  under  the  cla- 
vicle, and  in  front  of  the 
axillary  artery,  and  be- 
comes continuous  with 
a,  the  subclavian  vein. 
See  also.  Fig.  4,  t,  the 
axillary,  and  /,  the  sub- 
clavian veins. 

In  this  course  it  re- 
ceives the  circumflex  veins,  the  inferior  scapular,  the  long 
thoracic,  the  superior  thoracic,  and  the  acromial  veins. 

VOL.  II.  2 


10 


VASCULAR  SYSTEM 


The  subclavian  veins,  Fig.  4,  f,  u,  extend  from  the  infe- 
rior extremity  of  the  scalenus  anticus  muscle  to  the  supe- 


Fig.  1. 


rior  vena  cava,  but  they  present  differences  according  as 
they  are  examined  on  the  right  or  on  the  left  side,  on 
account  of  the  position  of,  g,  the  superior  vena  cava. 


OF  THE  VEINS. 


11 


Thus  the  right  subclavian  vein,  f,  is  very  short,  and  its 
size  is  always  less  than  that  of  the  left. 

The  left  subclavian  vein,  ii,  is  much  longer  than  the 
right,  and  receives  two  veins  which  the  right  does  not 
receive  ; viz.  the  left  internal  mammary  awl  the  left  inferi- 
or thyroid. 

That  part  of  the  left  subclavian  vein  nearest  the  descend- 
ing cava,  which  lies  before  the  trachea,  is  generally  known 
as  the  vena  mnominata. 

The  two  subclavian  veins  equally  receive  besides  the 
internal  and  the  external  jugular  veins,  the  vertebral  and 
the  superior  intercostal  veins. 

The  vertebral  vein  descends  in  the  canal  which  contains 
the  vertebral  artery,  and  issuing  from  thence  at  the  sixth 
or  seventh  cervical  vertebra  it  unites  with  another  consid- 
erable vein,  which  communicates  with  the  lateral  sinus  of 
the  dura  mater  by  the  mastoid  foramen.  After  this  union 
it  receives  numerous  branches  from  the  adjacent  muscles, 
and  opens  into  the  subclavian  vein. 

The  right  and  left  superior  intercostal  veins  also  dis- 
charge their  blood  into  the  subclavian  veins. 


SUPERIOR  VENA  CAVA,  g. 

The  superior  vena  cava  forms  the  grand  trunk  which 
transmits  the  blood  of  the  head,  the  neck,  the  superior 
extremities,  and  a portion  of  the  circulation  of  the  thorax, 
to  the  heart.  This  vein  commences  opposite  the  cartilage 
of  the  first  rib,  and  descends  to  the  base  of  the  pericardi- 
um, from  which  it  receives  a fibrous  sheath.  It  then  enters 
that  membranous  sac,  descends  vertically  on  the  right  of 
the  aorta,  and  opens  into  the  right  auricle  of  the  heart. 

Before  entering  the  pericardium  the  superior  vena  cava 
receives  the  following  branches  : — 


12 


VASCULAR  SYSTEM 


Fig.  5. 


1st.  The  right  internal  mammary  vein,  which  differs  from 
the  left  only  in  its  termination. 

2d.  The  inferior  thyroid  vein,  opening  into  the  superior 
vena  cava,  between  the  two  subclavian  veins. 

3d.  The  vena  azygos,  Fig. 

5,  a,  a,  a,  is  remarkable  for 
having  no  corresponding 
vein,  and  in  forming  a com- 
munication between  the  two 
venae  cavae.  It  opens  into 
the  superior  vena  cava  im- 
mediately above  the  right 
branches,  and  passing 
through  the  pillars  of  the 
diaphragm,  with  the  aorta 
and  thoracic  duct,  opens  in- 
to the  inferior  vena  cava,  or 
into  one  of  the  lumbar  veins. 

4th.  The  vena  azygos  at 
the  convexity  of  its  curve 
receives  the  right  bronchial 
vein,  and  anteriorly  branches 
from  the  aorta  and  oesopha- 
gus. To  the  right  it  receives 
the  corresponding  intercos- 
tal veins.  To  the  left,  to- 
wards the  seventh  rib,  the 
vena  semi-azygos,  a consi- 
derable branch  which  ascends  parallel  to  the  vena  azygos, 
on  the  left  side  of  the  vertebrae,  and  which  receives  the  in- 
ferior intercostal  veins  of  the  left  side. 


OF  THE  VEINS. 


13 


II.  VEINS  WHICH,  BY  THEIR  UNION,  FORM  THE  INFERIOR 
VENA  CAVA. 


1.  VEINS  WHICH,  BY  THEIR  UNION,  FORM  THE  EXTERNAL  ILIAC  VEINS. 

The  popliteal  vein,  commences  by  three  veins  which  ac- 
company the  anterior,  posterior  and  fibular  arteries  ; the 
external  saphena  vein  also  contributes  to  its  formation,  by 
collecting  the  blood  upon  the  front  and  outer  side  of  the 
foot,  and  passing  into  the  ham,  opens  into  the  popliteal 
vein. 

The  femoral  or  crural  vein  is  a continuation  of  the  pop- 
liteal vein  ; it  ascends  obliquely  at  the  inner  and  fore  part 
of  the  thigh,  close  to  the  femoral  artery,  following  the 
same  course  up  to  the  crural  arch.  In  its  progress  it  re- 
ceives a great  number  of  deep  branches,  precisely  similar 
to  those  of  the  artery,  and  the  following  remarkable  super- 
ficial branch : 


14 


VASCULAR  SYSTEM 


Tlie  internal  vena 
saphena,  Fig.  6,  col- 
lects the  blood  from 
the  inner  part  of,  a, 
the  foot  and  toes  ; 
it  is  united  to  the 
external  saphena  by 
a transverse  arch  ; 
these  united  branch- 
es ascend  before 
the  inner  ancle,  and 
form  a trunk  which 
is  continued  on  the 
inner  part  of  the 
leg,  and  passing  be- 
hind the  inner  con- 
dyle of  the  femur, 
it  proceeds  on  the 
inside  of  the  thigh 
to  an  opening  in  the 
fascia  lata,  b,  where 
it  discharges  itself 
into,  c,  the  femoral 
vein.  At  this  part 
it  receives  several 
superficial  abdomi- 
nal veins,  the  cir- 
cumflex  iliac  vein, 
and  the  external 
pudic  veins. 

The  external  il- 
iac vein  receives 
branches  corres- 
ponding to  the  artery  of  the  same  name,  and  in  the  male 
it  receives  a large  vein  w'hich  originates  in  the  envelope  of 
the  testicle. 


OF  THE  VEINS. 


15 


2.  THE  VEINS  WHICH,  BY  THEIR  UNION,  FORM  THE  INTERNAL  ILIAC 

VEIN. 

The  internal  iliac  vein,  Fig.  4,  s,  s,  is  situated  in  the 
cavity  of  the  pelvis,  behind  the  artery  of  the  same  name  ; 
its  branches  correspond  exactly  to  those  of  the  artery,  with 
the  exception  of  the  following  : 

The  vesical  veins  are  large  and  very  numerous,  but  differ 
according  to  the  sex  of  the  subject  we  examine. 

In  the  male  they  commence  upon  the  glands  and  unite 
into  two  trunks,  the  dorsal  veins  of  the  penis,  which  run 
♦upon  the  back  of  that  organ,  and  afterwards  wind  down- 
wards upon  the  organs  of  generation,  and  continuing  their 
course  on  the  sides  of  the  bladder,  and  over  the  prostate 
gland,  open  into  the  internal  iliac  vein. 

In  the  female  the  vesical  veins  commence  by  the  veins 
of  the  clitoris  and  the  labia,  and  unite  with  the  numerous 
vessels  of  the  vagina  and  rectum. 

The  sacro-lateral  veins,  communicate  in  the  sacral  canal 
with  the  vertebral  sinuses,  and  emerging  from  the  anterior 
sacral  foramina  join  the  internal  iliac  vein. 


COMMON  ILIAC  VEINS. 

The  common  iliac  veins  result  from  the  union  of  the  ex- 
ternal and  internal  veins  ; they  extend  from  the  sacro-iliac 
symphysis  to  the  fifth  lumbar  vertebra,  where  they  give  rise 
to  the  inferior  vena  cava. 


INFERIOR  VENA  CAVA.  Fig.  4,  tl,  T. 

The  inferior  vena  cava  is  larger  than  the  superior,  and 
extends  from  the  articulation  of  the  fourth  and  fifth  lumbar 


16 


VASCULAR  SYSTEM 


vertebr.Te  to  the  right  auricle  of  the  heart.  It  ascends 
on  the  right  side  of  the  bodies  of  the  lumbar  vertebrae, 
passes  above  and  behind  the  liver,  and  advancing  through 
a wide  aperture  of  the  aponeurosis  of  the  diaphragm,  in- 
troduces itself  into  the  pericardium,  and  enters  the  right 
auricle  of  the  heart  by  an  aperture  which  is  bounded  by 
the  Eustachian  valve.  '' 


BRANCHES  OF  THE  INFERIOR  VENA  CAVA. 

The  middle  sacral  vein  ascends  upon  the  coccyx  and 
sacrum,  in  the  angle  formed  by  the  union  of  the  common 
iliac  veins. 

The  lumbar  veins  are  four  in  number  on  each  side,  and 
commence  by  an  abdominal  branch,  and  a dorsal  branch, 
corresponding  to  the  branches  of  the  lumbar  arteries;  the 
dorsal  communicates  by  the  intervertebral  foramina,  with 
the  vertebral  sinuses.  The  lumbar  veins  of  the  left  side 
pass  under  the  aorta  and  are  in  consequence  longer  than 
the  right. 

The  spermatic  veins,  see  Fig.  4,  r,  differ  in  their  origin 
in  the  two  sexes.  In  the  male  they  commence  by  the 
spermatic  plexus,  tlie  roots  of  which  are  expanded  in  the 
testicle,  they  anastomose  with  the  neighboring  veins,  and 
collect  into  four  or  five  branches,  which  envelope  the 
vas  deferens,  and  passing  through  the  inguinal  ring,  unite 
and  form  a single  trunk,  which  extends  upwards  and 
inwards  on  the  psoas  muscle,  as  far  as  the  upper  part  of 
the  pelvis,  where  the  spermatic  vein  forms  another  plexus 
named  the  corpus  pamjnnif orme  : these  veins  again  unite 
and  convey  their  blood  into  the  inferior  vena  cava  on  the 
right  side,  and  into  the  corresponding  renal  vein  on  the 
left  side. 

In  the  female,  the  spermatic  veins  originate  in  the  ovari- 


OF  THE  VEINS. 


17 


um,  Fallopian  tube,  ligamentum  teres,  and  sides  of  the 
uterus ; they  afterwards  collect  between  the  laminae  of  the 
broad  ligament  of  the  uterus,  and  then  follow  the  same 
course  as  in  the  male. 

The  renal  veins,  see  Fig.  4,  o,  o,  are  of  great  size.  Their 
roots  exactly  correspond  to  the  minute  ramifications  of  the 
renal  arteries.  They  unite  in  the  fissure  of  p,  p,  the  kid- 
neys, into  several  branches,  which  collect  into  a trunk 
opening  into  the  cava. 

The  capsular  and  adipose  veins  frequently  open  into  the 
renal  veins,  and  in  other  respects  have  the  same  disposition 
as  the  arteries  to  which  they  correspond. 

The  hepatic  veins  have  their  roots  in  the  substance  of 
the  liver:  some  of  them  are  of  small  size  and  enter  the 
vena  cava  separately ; others,  namely,  the  middle  hepatic 
veins,  open  into  the  vena  cava  between  the  right  and  left 
hepatic  veins. 

The  middle  hepatic  veins  open  into  the  vena  cava  be- 
tween the  right  and  left  hepatic  veins. 

The  left  hepatic  veins  ramify  in  the  left  lobe  of  the  liver, 
and  proceed  from  thence  into  the  vena  cava,  opposite  the 
aperture  of  the  diaphragm,  through  which  it  passes. 

The  right  hepatic  veins  issue  from  the  right  lobe  of  the 
liver,  and  open  into  the  vena  cava  below  the  preceding. 

The  inferior  diaphragmatic  veins  are  two  in  number, 
and  are  similar  to  the  arteries  of  the  same  name. 

VERTEBRAL  SINUSES  AND  VEINS  OF  THE  SPINAL  MARROW. 

There  exist  in  the  whole  length  of  the  vertebral  cavity 
two  great  venous  canals,  named  the  vertebral  sinuses,  and 
which  communicate  with  the  internal  jugular  vein.  These 
sinuses  have  the  same  structure  as  the  sinuses  of  the  dura 
mater,  in  being  traversed  in  various  directions  by  irregularly 
distributed  membranous  bridles. 

3 


VOL.  II. 


18 


VASCULAR  SYSTEM 


At  their  inner  side,  they  communicate  with  each  other 
by  traiisverse  sinuses,  occupying  the  middle  of  the  body  of 
each  vertebra,  then  passing  under  the  posterior  vertebral 
ligament,  they  receive  the  veins  which  transmit  the  blood 
from  the  envelopes  of  the  spinal  marrow,  and  the  spongy 
tissue  of  the  vertebr®. 

The  veins  of  the  syinal  marroio  accompany  the  arteries 
of  that  name,  and  open  into  the  inferior  cerebellar  veins. 

The  veins  of  the  sacral  canal  are  of  considerable  size  ; 
they  are  immersed  in  cellular  tissue,  and  have  no  adhesion 
to  the  osseous  parts.  Their  inferior  extremities  are  lost  in 
very  delicate  ramifications  upon  the  os  coccygis.  Exter- 
nally, they  form  communications  with  the  lateral  sacral 
veins  ; and,  internally,  their  transverse  branches  anasto- 
mose with  each  other. 


VEINS  OP  THE  HEART. 

CORONARY  VEINS. 

The  great  right  coronary  vein  collects  the  blood  from 
the  apex  of  the  heart,  passes  into  the  groove  which  sepa- 
rates the  auricles  from  the  ventricles,  and  receives  a great 
number  of  lateral  branches  which  terminate  in  the  right 
auricle,  close  by  the  entrance  of  the  inferior  vena  cava, 
where  the  coronary  is  covered  by  a semilunar  valve. 

The  small  right  coronary  vein  unites  with  the  preceding, 
and  passes  in  the  same  direction  to  the  posterior  surface  of 
the  heart. 

The  left  coronary  veins  are  smaller  than  the  right. 
They  commence,  with  the  preceding,  at  the  apex  of  the 
heart,  by  numerous  roots,  which  unite,  upon  the  convex 
surface  of  that  organ,  into  a single  trunk,  which  discharges 
its  blood  with  the  other  veins  at  the  posterior  part  of  the 
right  auricle. 


OF  THE  VEINS. 


19 


There  are  a number  of  veins  which  terminate  directly  in 
the  cavity  of  the  right  side  of  the  heart,  by  minute  orifices, 
which  have  been  termed,  by  their  original  describer,  the 
foramina  thebesii. 

ABDOMINAL  DEPARTMENT  OF  THE  VENOUS  SYSTEM. 

VENA  PORT.E. 

BRANCHES  OF  THE  VENA  PORTA:. 

The  vena  portce  derives  its  blood  from  all  the  organs  of 
digestion  in  the  cavity  of  the  abdomen,  excepting  the  liver. 
It  is  formed  principally  by  three  large  trunks,  the  coronary 
vein  of  the  stomach,  the  splenic  and  the  mesenteric  veins, 
all  which  unite  to  form  the  middle  part  or  trunk  of  the 
vena  port®. 

The  coronary  vein  of  the  stomach  corresponds  to  the 
artery  of  the  same  name.  It  is  the  smallest  of  the  three 
branches.  It  empties  into  the  trunk  of  the  vena  portae, 
behind  the  pyloric  portion  of  the  stomach. 

The  splenic  vein  collects  the  blood  from  the  spleen  by  a 
number  of  branches,  which,  after  a short  course,  unite 
upon  the  pancreas  into  a single  trunk,  which  extends  from 
left  to  right  to  unite  with  the  superior  mesenteric  vein,  op- 
posite the  vertebral  column.  It  likewise  receives  the  veins 
which  correspond  to  the  vasa  breviora,  the  right  and  left 
gastro-epiploic,  the  duodenal,  and  the  pancreatic  veins,  and 
the  small  mesenteric  vein.  The  last  named  vein  receives 
the  blood  from  the  left  part  of  the  colon  and  the  rectum. 
Its  branches  correspond  to  those  of  the  inferior  mesenteric 
artery. 

The  superior  mesenteric  vein  is  distributed  in  the  same 
manner  as  that  of  the  artery  of  the  same  name,  to  the 
right,  and  a little  in  front,  of  which  it  is  placed.  It  is 


20 


VASCULAR  SYSTEBI 


formed  by  the  veins  of  the  small  intestines,  and  by  those 
which  correspond  to  the  right  colic  arteries  ; and  in  the 
mesentery  it  constitutes  a net-work,  very  similar  to  the 
ramifications  of  the  artery.  At  the  edge  of  the  transverse 
mesocolon,  the  trunk  of  this  vein,  after  receiving  several 
branches  from  the  duodenum  and  pancreas,  unites  with  the 
splenic  vein. 

The  trunli  of  the  vena  joortce  is  formed  by  the  junction 
of  the  splenic  and  superior  mesenteric  veins  with  the  coro- 
nary vein  of  the  stomach  ; it  extends  from  the  vertebral 
column  to  the  groove  of  the  liver,  and  separating  into  two 
branches,  nearly  at  a right  angle,  seems  to  form  under  the 
liver  a horizontal  canal,  which  has  been  termed  the  sinus  of 
the  vena  portce.  These  vessels  are  extended  through  the 
lobes  of  the  liver  in  innumerable  ramifications.  In  its  pas- 
sage under  the  small  extremity  of  the  pancreas,  it  is  united 
to  the  cystic  and  hepatic  ducts,  the  hepatic  artery,  and  a 
number  of  nervous  filaments  and  lymphatic  vessels  ; all 
which  are  surrounded  by  a fibrous  envelope  named  the 
capsule  of  glisson. 

Injections  thrown  into  the  vena  portae  penetrate  into  the 
other  vessels  of  the  liver,  and  vice  versa. 


OF  THE  VEINS. 


21 


CHAP.  III. 

OF  THE  CAPILLARIES. 

The  delicate  branches  of  the  final  ramifications  of  the 
arteries  and  of  the  minute  origins  of  the  veins,  are  called 
the  capillaries.  In  these  small  vessels  most  of  the  im- 
portant functions  of  life  take  place,  as  secretion,  nutrition, 
exhalation,  calorification,  &c.  They  are  of  such  extreme 
tenuity  that  they  escape  detection  by  the  naked  eye. 
Their  existence  may  be  demonstrated  not  only  by  micro- 
scopical observation  as  observed  in  the  last  chapter,  but  by 
the  fact,  that  a colored  fluid  may  be  thrown  from  the 
arteries  into  the  veins,  without  any  extravasation  between 
them. 

There  are  two  parts  in  the  capillary  system.  One  is 
diffused  over  the  whole  body,  being  placed  between  the 
terminating  branches  of  the  arteries  and  the  roots  of  the 
veins,  the  other  part  is  between  the  minute  ramifications  of 
the  pulmonary  arteries  and  the  origins  of  the  pulmonary 
veins.  In  the  first  the  arterial  blood  is  changed  to  venous  ; 
in  the  last,  the  reverse.  Their  intimate  organization  is 
unknown. 

Though  these  capillaries  exist  everywhere  in  the  body, 
still  they  are  more  or  less  numerous  in  the  various  organs. 
They  are  more  abundant  in  the  secretory  organs,  the  skin, 
the  mucous  membranes,  and  the  lungs,  and  less  so  in  the 
fibrous  structures  ; in  short  the  capillary  system  is  as  much 
more  developed  in  a part,  says  Bichat,  as  it  has  more  func- 
tions to  sustain,  and  do  not  exist  in  organs  in  proportion 
to  their  size. 


ART.  VI. 


CHAP.  I. 

ORGANS  OF  ABSORPTION. 

The  organs  of  absorption  consist  of  lymphatic  vessels 
and  lymphatic  glands ; the  latter  also  are  named  lymphatic 
ganglia.  This  system  of  vessels  was  perfectly  unknown 
until  a celebrated  anatomist  of  the  name  of  Asellius,  in 
the  year  1622,  discovered,  upon  the  mesentery  of  a dog, 
white  lines  extending  from  the  intestine  to  the  glands.  He 
observed  that  they  contained  a milk-like  fluid,  and  hence 
termed  them  lacteals.  By  a series  of  experiments  he  found 
that  these  vessels  absorbed  the  chyle,  and  conveyed  it  to 
the  blood  ; and  subsequent  inquiries  proved  that  the  same 
system  of  vessels  was  minutely  distributed  over  the  whole 
human  frame ; and  that,  at  the  angle  formed  by  the  union 
of  the  subclavian  with  the  internal  jugular  vein,  upon  either 
side  of  the  neck,  one  or  more  of  these  vessels  discharges 
their  contents  into  the  current  of  blood. 

The  lymphatic  vessels  are  small  pellucid  tubes,  which 
occur  in  all  parts  of  the  body ; they  originate  on  the  sur- 
face of  the  membranes,  and  in  the  tissue  of  all  the  organ- 
ized structures  ; and  they  transport  all  the  absorbed  fluids 
to  the  venous  system.  Those  absorbents  which  take  up 


LYMPHATIC  SYSTEM. 


23 


the  chyle  in  the  intestines,  during  the  process  of  digestion, 
are  named  lacteals ; and,  although  they  differ  in  their  uses 
from  the  other  absorbent  vessels,  they  have  precisely  the 
same  anatomical  character. 

The  ultimate  arrangement  of  the  lymphatic  vessels  has 
not  been  demonstrated,  but  the  whole  exterior  of  the  body 
is  known  to  be  covered  by  a net-work  of  these  vessels, 
placed  in  the  subjacent  cellular  tissue,  and  others  occupy 
the  muscular  intervals  and  organs  of  the  body ; nor  is  this 
system  of  vessels  confined  to  the  limbs  only,  for  it  exists 
in  the  surface  and  substance  of  each  particular  organ,  as 
in  the  lungs,  liver,  spleen,  pancreas,  and  other  viscera, 
where  both  superficial  and  deep  seated  lymphatics  are  uni- 
formly distributed. 

Generally  these  vessels  are  straight  in  their  course,  but 
their  communications  with  each  other  are  very  numerous, 
and  they  frequently  form  successive  meshes.  They  are 
also  remarkable  for  their  alternate  unions  and  divisions,  so 
that  a great  number  of  vessels,  after  being  collected  into  a 
single  trunk,  separate  a second  time,  and  again  form  one  or 
more  trunks,  which  appear  most  conspicuous  in  the  vicinity 
of  their  glands. 


THORACIC  DUCT. 

All  the  absorbent  vessels  discharge  themselves  into  the 
subclavian  and  internal  jugular  veins,  by  considerable 
trunks,  called  the  thoracic  duct,  and  great  right  lymphatic 
duct.  These  convey  the  absorbed  fluids  into  the  circula- 
tion. See  Fig.  5,  d,  the  left,  and  f,  the  right  thoracic 
ducts. 


24 


LYMPHATIC  SYSTEM. 


STRUCTURE  OF  THE  LYMPHATIC  VESSELS. 

The  lymphatic  vessels  are  formed  of  an  external  cellular 
membrane,  and  an  internal  membrane  similar  to  that  of 
the  veins  ; the  latter  is  folded  upon  itself,  producing  valves 
at  intervals,  which  are  generally  disposed  in  pairs.  These 
valves  are  usually  more  numerous  as  the  vessels  diminish 
in  caliber.  So  that  the  thoracic  canal  contains  fewer  than 
the  others. 


LYMPHATIC  GLANDS  IN  GENERAL. 

The  branches  of  the  principal  lymphatic  trunks  traverse 
a greater  or  less  number  of  lymphatic  glands ; that  is  to 
say,  small  bodies  of  various  forms  and  size,  and  collected 
together  in  greater  or  less  quantity,  or  sometimes  isolated. 
These  glands  are  not  numerous  in  the  extremities,  but  they 
occur  abundantly  in  the  thorax  and  abdomen.  Each  gland 
receives  lymphatic  vessels,  which  subdivide  and  form  an 
inextricable  interlacement,  which  is  lost  in  its  substance, 
without  our  being  able  to  trace  its  distribution,  or  display 
the  minute  structure.  These  glands  vary  in  diameter  from 
the  twentieth  of  an  inch  to  an  inch.  They  are  in  gen- 
eral red  and  vascular ; some,  however,  are  of  a gray  or 
blackish  color.  These  bodies  have  been  denominated  also 
lymphatic  ganglions,  because  some  anatomists  have  sup- 
posed, th<y;  they  bear  the  same  relation  to  their  vessels,  as 
the  nervous  ganglions  do  to  the  nerves. 

The  absorbents  which  enter  the  glands  are  called  vasa 
inferentia,  and  those  which  pass  out  of  them,  are  termed 
vasa  effcrentia. 


LYMPHATIC  SYSTEM. 


25 


Fig.  7,  a lymphatic  vessel. 

Fig.  8,  a lymphatic  vessel  laid  open,  shewing  its  valves. 

Fig.  9,  lymphatic  vessels  and  their  glands. 

LYMPHATIC  GLANDS  IN  PARTICULAR. 

LYMPHATIC  GLANDS  OF  THE  INFERIOR  EXTREMITIES. 

The  anterior  tihial  gland  is  the  only  gland  in  the  leg. 
It  is  found  between  the  tibia  and  fibula,  on  the  lower  ex- 
tremity of  the  inter-osseous  ligament. 

The  popliteal  glands  are  three  or  four  in  number,  and 
are  situated  in  the  ham.  ' 

The  inguinal  glands  are  situated  on  the  upper  part  of 
the  thigh,  and  in  the  groin ; the  superficial  are  found  be- 
tween the  skin  and  aponeurosis,  surrounding  the  termi- 
nation of  the  internal  saphena  vein  ; their  number  varies 
from  eight  to  twelve,  and  they  are  sometimes  observed 
4 


VOL.  II. 


26 


LYMPHATIC  SYSTEM. 


to  form  a chain  of  glands,  extending  from  the  middle  and 
inner  part  of  the  tliigh  to  the  groin. 

There  are  three  of  four  deef  seated  inguinal  glands, 
situated  under  the  aponeurosis,  and  about  the  femoral 
artery. 

LYMPHATIC  GLANDS  OF  THE  PELVIS. 

The  hypogastric  glands,  ten  or  fifteen  in  number,  are 
situated  in  the  lateral  parts  of  the  cavity  of  the  pelvis,  and 
about  the  internal  iliac  vessels. 

On  the  outside  of  the  pelvis,  very  small  lymphatic  glands 
are  met  with  in  the  course  of  the  glutaeal  and  ischiatic 
arteries  ; and  in  the  interior  of  the  pelvis,  a number  of 
minute  glands  are  found  upon  the  bladder,  the  uterus,  and 
the  vesiculae  seminales. 

The  sacral  glands  are  situated  in  the  hollow  of  the 
sacrum,  between  the  laminae  of  the  meso-rectum. 

The  external  iliac  glands  vary  in  number  from  six  to 
fifteen,  they  are  situated  in  the  course  of  the  external  iliac 
vessels,  and  form  a chain  of  glands  extending  from  the 
crural  arch  to  the  lower  part  of  the  vertebral  column. 


LYMPHATIC  GLANDS  OF  THE  ABDOMEN. 

The  lumbar  glands  are  large  and  numerous  ; they  occupy 
the  region  of  the  loins,  and  surround  the  aorta  and  the  in- 
ferior vena  cava ; they  are  also  situated  upon  the  crura  of 
the  diaphragm,  and  are  thickly  arranged  over  the  renal 
arteries.  These  glands  furnish  vessels  which  immediately 
communicate  with  the  thoracic  duct. 

The  hepatic,  pancreatic,  and  splenic  glands  are  situated 
,round  the  vena  portm  and  along  the  splenic  artery ; they 


LYMPHATIC  SYSTEM. 


27 


receive  the  lymphatic  vessels  of  the  liver,  aorta,  and  pan- 
creas. 

The  mesenteric  glands  are  numerous,  sometimes  exceed- 
ing a hundred,  and  are  in  general  of  considerable  size  ; 
they  are  situated  between  the  two  laminae  of  the  mesen- 
tery, and  receive  the  lacteals  or  absorbents  of  the  chyle. 
See  Fig.  11,  c,  d. 

The  mesocoKc  glands  are  fewer  than  the  preceding,  and 
are  placed  between  the  laminae  of  the  mesocolon. 

The  gastro-epipioic  glands  occupy  the  greater  and  small- 
er curvature  of  the  stomach ; they  surround  the  gastro- 
epiploic arteries,  and  the  coronary  artery  of  the  stomach. 


LYMPHATIC  GLANDS  OF  THE  THORAX. 

glands  of  the  mediastinum.  Upon  the  diaphragm 
and  pericardium  there  are  six  or  eight  of  these  bodies  ; 
and  there  are  twelve  or  sixteen  surrounding  the  thymus 
gland,  and  large  vessels  of  the  base  of  the  heart. 

The  bronchial  glands  are  very  numerous  ; they  are 
situated  before  the  division  of  the  trachea,  around  the 
bronchi,  and  even  in  the  interior  of  the  lungs ; but  they 
will  be  more  particularly  noticed  in  the  description  of  the 
trachea  and  bronchi. 


LYMPHATIC  GLANDS  OF  THE  SUPERIOR  EXTREMITY. 

The  glands  of  the  arm  are  distributed  in  the  line  of  the 
brachial  artery ; they  are  not  often  met  with  in  the  fore- 
arm, although,  not  unfrequently,  we  find  a few  at  the  bend 
of  the  arm  near  the  inner  condyle. 

The  axillary  glands  are  situated  in  the  cellular  tissue 
of  the  armpit,  around  the  axillary  vessels  and  their- 


28 


LYMPHATIC  SYSTEM. 


branches ; they  are  of  large  size,  and  vary  from  six  to 
twelve  in  number.  Some  are  met  with  under  the  collar 
bone  and  between  the  ribs. 

LYMPHATIC  GLANDS  OF  THE  HEAD  AND  NECK. 

The  glands  of  the  sJcull  are  few  in  number  ; several  small 
glands  are  found  behind  the  ear,  and  two  or  three  are  also 
observed  under  the  zygomatic  arch.  No  lymphatic  glands 
have  been  traced  in  the  interior  of  the  skull. 

The  glands  of  the  face  are  situated  upon  the  buccinator 
muscle,  and  along  the  base  of  the  jaw.  where  they  sur- 
round the  anterior  portion  of  the  digastric  muscle. 

glands  of  the  neck  are  superficial  and  deep/  seated; 
the  former  are  situated  beneath  the  platysma  myoides,  in 
the  course  of  the  external  jugular  vein  and  its  branches. 
The  others,  called  glandulce  concatenate,  occur  in  the  vici- 
nity of  the  internal  jugular  vein  and  common  carotid 
artery.  Their  size  is  small,  but  their  number  is  very  great. 
In  children  they  frequently  present  a kind  of  knotty  cord, 
extending  from  behind  the  ear  to  the  collar  bone. 


LYMPHATIC  SYSTEM. 


29 


CHAP.  II. 

PARTICULAR  LYMPHATIC  VESSELS. 

LYMPHATIC  VESSELS  WHICH  TERMINATE  IN  THE  THORACIC 

DUCT. 

1.  LYMPHATICS  OF  THE  INFERIOR  EXTREMITY'. 

The  superficial  lymphatics  of  the  lower  extremities  con- 
sist of  very  numerous  vessels,  which  are  found  in  the 
cellular  tissue,  between  the  skin  and  muscles.  Their  com- 
mencement can  be  traced  with  little  difficulty  in  the  toes, 
round  which  they  form  a very  delicate  plexus,  and  form  by 
their  successive  union  from  sixteen  to  twenty  branches, 
which  cover  the  surface  of  the  foot  and  pass  up  the  inner 
side  of  the  leg;  those  of  the  side  of  the  foot  collect  and 
form  two  or  three  branches,  which  ascend  around  the 
tendo  Achilles. 

Thus  united,  the  principal  trunks  of  the  lymphatics  of 
the  leg  pass  over  the  calf,  and  the  ham,  and  ascend  upon 
the  inner  and  outer  side  of  the  thigh,  approaching  each 
other  and  continually  communicating,  until,  at  length, 
they  terminate  in  the  superficial  inguinal  glands. 


30 


LYMPHATIC  SYSTEM. 


Fig.  10,  the  lymphatic  Fig.io. 

vessels  of  the  inner  part 
of  the  thigh. 

All  these  vessels  are 
immersed  in  the  subcu- 
taneous cellular  tissue  ; 
and  their  communica- 
tions are  so  frequent 
and  numerous,  tliat  they 
form,  upon  the  foot,  leg 
and  thigh,  a net-work 
which  completely  sur- 
rounds these  parts. 

The  deep  Jpnphatic 
vessels  of  the  lower  ex- 
tremities may  be  distin- 
guished into  four  series  : 
namely,  the  anterior 
tibial,  the  'posterior  tihi- 
al,  and  the  filmlar  lijm- 
phatics,  according  as 
they  accompany  the  an- 
terior and  posterior  tibial 
and  fibular  arteries. 

They  terminate  in  the 
popliteal  glands.  In- 
deed most  of  the  deep 
seated  lymphatics  of 
the  leg  and  foot  have 
the  same  termination. 

These  glands  are  con- 
nected together  by  a great  number  of  smaller  vessels, 
which  form  a plexus,  whence  issue  several  trunks  which 
ascend  upon  the  popliteal  and  femoral  vessels,  receiving 
all  the  deep  lymphatics  of  the  thigh,  and  subdividing  up 
to,  a,  the  deep  inguinal  glands. 


LYMPHATIC  SYSTEM. 


31 


9.  SUPERFICIAL  LVMPHATIC  VESSELS  OF  THE  HIPS,  P£RIN.<EUM,  LOINS, 
EXTERNAL  PARTS  OF  GENERATION,  ETC. 

The  lymphatics  of  the  hips  are  numerous,  and  pass  over 
the  outer  and  inner  part  of  the  thigh,  to  unite  with  the 
superficial  absorbents  of  the  perinaeum,  and  inguinal 
glands. 

The  lymphatics  of  the  loins  descend  from  the  lumbar 
vertebras  over  the  crest  of  the  ilium,  and  divide  in  the 
superficial  inguinal  glands. 

The  lymphatics  of  the  lower  part  of  the  parieties  of  the 
abdomen  commence  on  the  level  of  the  umbilicus,  and 
form  a net-work  over  the  whole  anterior  region  of  the 
abdomen  ; they  collect  inferiorly  into  a few  trunks  which 
terminate  in  the  superficial  glands. 

The  lymphatics  of  the  perinceum,  scrotum,  and  penis,  are 
very  numerous  ; those  of  the  scrotum  ascend  on  each  side 
to  the  inner  part  of  the  thigh,  where  they  unite  with  those 
of  the  perinaeum  and  penis  ; they  all  terminate  in  the 
superficial  glands. 

In  the  female,  the  lymphatics  of  the  external  parts  of 
the  organs  of  generation  have  the  same  termination. 

3.  DEEP  SEATED  OBTURATOR,  ISCHIATIC,  AND  GENITAL  LYMPHATIC 

VESSELS. 

The  obturator  lymphatics  are  distributed  over  the  adduct- 
or muscles  and  neighboring  parts,  and  take  the  direction 
of  the  obturator  artery,  through  the  obturator  foramen,  to 
terminate  in  the  hypogastric  glands. 

The  ischiatic  lymphatics  are  distributed  to  the  muscles 
of  the  pelvis,  and  terminate  in  the  same  glands  as  the 
former. 

The  glutwal  lymphatics  have  the  same  distribution  as  the 


32 


LY^^PHATIC  SYSTEM. 


glutseal  artery,  and,  passing  into  the  pelvis,  terminate  in 
the  same  glands  as  the  preceding. 

The  dec]}  lymphatics  of  the  penis  and  clitoris  follow  the 
course  of  the  interal  pudic  artery,  and  terminate  in  the 
same  glands. 

The  lymphatics  of  the  testicle  are  numerous,  and  are 
among  the  largest  of  the  body ; some  of  them  are  the  size 
of  a crow-quill  : they  unite  upon  the  spermatic  cord  into 
six  or  eight  branches,  and  ascend  with  it  towards  the  in- 
guinal ring,  through  which  they  pass  to  follow  the  sper- 
matic artery,  and  terminate  in  the  lumbar  glands. 

The  lymphatics  of  the  prostate  gland  and  vesiculce  semi- 
nales  unite  with  those  of  the  bladder,  and  enter  into  the 
hypogastric  glands. 

The  lymphatics  of  the  uterus  unite  with  those  which  are 
distributed  to  the  vagina,  to  terminate  in  the  same  glands. 
Those  which  are  found  upon  the  broad  ligament  and  ova- 
rium, ascend  with  the  spermatic  lymphatics  to  the  lumbar 
glands. 


4.  LYMPHATIC  VESSELS  OF  THE  URINARY  ORGANS. 

The  lymphatics  of  the  bladder  follow  the  course  of  its 
blood  vessels,  and  open  into  the  hypogastric  glands. 

The  lymphatics  of  the  Iddneys  unite  towards  their  fissure, 
and  then  proceed  upon  the  sides  of  the  aorta  to  the  lumbar 
glands.  The  ureters  also  are  furnished  with  numerous 
absorbents,  which  surround  those  tubes,  and  communicate 
freely  with  each  other,  and  with  the  last  named  glands. 

The  capsidar  lymphatics  proceed  to  the  hepatic  and 
splenic  glands,  and  several  pass  to  the  glands  upon  the 
pillar  of  the  diaphragm. 


LYMPHATIC  SYSTEM. 


33 


5.  LYMPHATIC  VESSELS  OF  THE  PARIETES  OF  THE  PELVIS  AND  AB- 
DOMEN. 

The  ileo-lumbar  lymphatics  are  a set  of  absorbents  which 
originate  in  the  iliacus  muscle,  and  upon  the  hip  bone  ; 
they  pass  under  the  psoas  muscle,  and  communicating  with 
the  inferior  lumbar  glands,  contribute  to  the  formation  of 
the  external  iliac  lymphatic  plexus,  or  the  assemblage  of 
lymphatics  which  accompany  the  external  iliac  vessels. 

The  sacral  lymphatics  are  extended  over  the  adipose 
tissue  of  the  rectum,  and  region  of  the  sacrum  ; they 
terminate  in  the  inferior  lumbar  or  hypogastric  glands. 
Those  lymphatics,  which  contribute  to  form  the  hypogastric 
plexus,  are  placed  on  the  sides  of  the  pelvis,  and  consist  of 
an  interlacement  of  vessels  and  glands,  in  which  the  obtu- 
rator, glutmal,  ischiatic,  uterine,  and  vesical  lymphatics 
terminate. 

The  epigastric  lymphatics  commence  in  the  vicinity  of 
the  umbilicus,  and  proceed  from  the  interior,  through  the 
abdominal  muscles  and  their  aponeuroses ; then  unite 
into  several  trunks,  which  descend  in  the  course  of  the 
epigastric  vessels,  and  terminate  in  the  external  iliac  plexus. 

The  circumflex  iliac  lymphatics  are  distributed  in  the 
integuments  of  the  sides  of  the  abdomen,  and  descend  to- 
wards the  crest  of  the  ilium,  to  one  of  the  external  iliac 
glands. 

The  lumbar  lymphatics  are  distributed  to  the  muscles  of 
the  lumbar  region,  but  they  unite  before  the  vertebral 
column,  where  their  numerous  communications,  with  those 
of  almost  all  the  other  trunks,  which  have  just  been  describ- 
ed, constitute  the  lumbar  lymphatic  plexus. 

5 


VOL.  II. 


34 


LYMPHATIC  SYSTEM. 


6.  LYMPHATIC  VESSELS  OF  THE  STOMACH  AND  INTESTINES. 

The  lymphatics  of  the  stomach  are  distributed  into  two 
distinct  orders  ; the  superfcial,  which  are  situated  beneath 
the  peritoneal,  and  the  deep,  which  are  distributed  to  the 
muscular  and  mucous  membranes.  Some  of  these  com- 
mence at  the  large  extremity  of  the  stomach,  and  join  the 
lymphatics  of  the  spleen  ; others  proceed  from  the  small 
curvature  of  the  stomach,  and  communicate  with  the 
glands  in  that  situation,  and  in  the  vicinity  of  the  liver. 
After  this,  they  descend  behind  the  pancreas  to  the  roots 
of  the  thoracic  duct. 

Although  in  some  animals  these  vessels  have  been  found 
to  contain  chyle,  in  the  human  subject  they  have  never 
been  observed  to  be  filled  with  it. 

The  lymphatics  of  the  intestines  are  usually  called  the 
LACTEALs,  on  account  of  their  conveying  a fluid  like  milk 
from  the  intestines  to  the  thoracic  duct.  Each  lacteal 
takes  its  origin  from  the  villi  of  the  intestines,  by  numer- 
ous short  radiated  branches,  and  each  branch  is  furnished 
with  an  orifice  for  imbibing  the  chyle.  ^ 

From  the  villi,  the  lacteals  pass  under  the  muscular 
membrane  of  the  intestines,  and  then  obliquely  through  it, 
uniting  in  their  course  into  larger  branches,  following  the 
course  of  the  mesenteric  blood  vessels.  They  are  found 
situated  on  each  side  of  the  arteries. 

It  is  observed  that  there  are  a much  greater  number  of 
lymphatics  in  the  small  intestines  than  in  the  large ; the 
descending  colon  and  rectum  present  but  few  aborbents, 
and  these  are  connected  with  the  lumbar  and  hypogastric 
glands,  or  those  of  the  mesorectum. 

The  lacteals  of  the  small  intestines,  after  passing  through 
the  different  glands  of  the  mesentery,  form  several  trunks, 


LYMPHATIC  SYSTE3I. 


35 


which  accompany  the  superior  mesenteric  artery,  until  they 
arrive  at  the  thoracic  duct. 

Fig.  11. 


h 


Fig.  11,  a,  a,  part  of  the  small  intestine;  b,  h,  lacteals ; 
c,  the  mesentery  ; d,  the  mesenteric  glands. 

The  lymphatics  of  the  great  omentum  ascend  to  unite 
with  the  lymphatics  of  the  stomach,  and  terminate  in  the 
glands  of  the  great  curvature. 


36 


LYMPHATIC  SYSTEM. 


7.  LVMPIIATIC  VESSELS  OF  THE  SPLEEN,  PANCKEAS,  AND  LIVEIL 

The  lymphatics  of  the  spleen  are  very  numerous  ; the 
superficial  and  deep  branches,  uniting  at  its  fissure  into  a 
few  trunks,  form  a plexus  round  the  splenic  vessels,  and 
pass  beneath  the  duodenal  extremity  of  the  pancreas,  to 
the  inferior  lymphatics  of  the  liver. 

The  lymphatics  of  the  pancreas  proceed  from  the  sub- 
stance of  that  gland,  and  unite  with  the  lymphatics  of  the 
spleen  and  stomach. 

The  lymphatics  of  the  liver  are  extremely  numerous,  nor 
does  any  organ  in  the  body  appear  to  contain  so  many  ; 
and,  like  those  of  the  other  viscera,  it  has  a superficial  and 
a deep  seated  series,  which,  however,  so  freely  communi- 
cate, that,  upon  injecting  the  external  lymphatics,  the  deep 
internal  are  readily  filled  from  them.  On  the  right  lobe 
they  collect  into  four  fasciculi  ; the  first  is  formed  by  the 
lymphatic  vessels,  which  commence  between  the  laminae  of 
the  suspensory  ligament,  and,  uniting  into  two  or  three 
trunks,  enter  the  thorax  near  the  ensiform  cartilage, 
traverse  some  of  the  glands,  and  open  into  the  thoracic 
duct  near  the  left  internal  jugular  vein.  The  second 
traverses  the  right  lateral  ligament  of  the  liver,  and  divides 
into  two  series ; the  one  superior,  which  mounts  into  the 
thorax,  and  afterwards  returns  into  the  abdomen  with  the 
aorta,  to  terminate  in  the  neighboring  glands  ; the  other 
inferior,  which  extends  along  the  last  ribs,  and  unites  with 
the  intercostal  lymphatics,  to  open  into  the  thoracic  duct. 
The  third  fasciculus  is  distributed  to  the  middle  of  the 
right  lobe,  and  unites  with  the  preceding  at  the  posterior 
part  of  the  liver.  The  fourth  fasciculus  commences  in  the 
anterior  part  of  the  right  lobe,  and  unites  with  the  deep 
series,  and  with  some  glands  near  the  pylorus. 

In  the  left  lobe  of  the  liver,  the  lymphatics  unite  with 


LYMPHATIC  SYSTEM. 


37 


the  preceding  and  to  those  of  the  spleen  ; those  from  the 
posterior  part  of  the  left  lobe  descend  towards  the  cardia, 
and  proceed  to  the  glands  of  the  small  curvature  of  the 
stomach. 


8.  THE  THORACIC  DUCT.  See  Fig.  II. 

The  thoracic  duct,/,  is  the  canal  which  receives  the  lym- 
phatics from  the  lower  half  of  the  body,  the  interior  of  the 
chest,  the  left  upper  extremity,  and  the  left  side  of  the 
head  and  neck.  It  extends  from  the  second  or  third  lum- 
bar vertebra  as  far  as  the  left  subclavian  vein,  and  is  form- 
ed by  the  union  of,  g,  five  or  six  large  trunks,  the  result  of 
the  absorbent  plexus  of  the  abdomen.  Near  the  aortic 
aperture  of  the  diaphragm,  the  thoracic  duct  presents  a 
very  remarkable  enlargement,  e,  the  receptaculum  chyli, 
which  is  placed  at  the  anterior  and  left  part  of  the  second 
lumbar  vertebra,  behind,  h,  the  aorta.  Above  this  dilata- 
tion, the  thoracic  duct  ascends  into  the  chest,  entering  be- 
tween the  pillars  of  the  diaphragm,  with  the  aorta  on  the 
left  side,  and  the  vena  azygos  to  the  right.  It  then 
ascends  behind  the  arch  of  the  aorta,  and  arrives  at  the 
seventh  cervical  vertebra,  turns  inwards  and  downwards, 
then  passes  the  thyroid  artery,  and  the  left  internal  jugular 
vein,  and  opens  close  to  the  latter  into  the  subclavian  vein 
of  the  same  side.  At  its  aperture  there  are  two  valves 
which  prevent  the  blood  from  passing  from  the  vein  into 
the  duct. 

Although  the  lymphatics  have  hitherto  been  described 
by  anatomists  as  collecting  into  trunks  to  transmit  their 
contents  into  the  subclavians  only ; Magendie*  and  a 
few  other  celebrated  physiologists  and  experimentalists 

* Magendie,  in  his  Physiology,  relates  some  very  curious  and  striking 
experiments,  which,  if  confirmed  by  others,  must  set  the  question  at  rest. 


38 


LYMPHATIC  SYSTEM. 


are  of  opinion,  that  many  other  communications,  between 
the  lymphatics  and  veins,  take  place  in  the  extremities 
and  other  parts  of  the  body.  Professor  Mayo  seems 
to  have  arrived  at  the  same  conclusion  ; I give  his  own 
words.  “ For  my  own  part,  I think  it  likely,  that  such 
communications  do  exist.  At  all  events,  when  believing 
that  they  did  not,  I have  witnessed  the  mercury  thrown 
into  the  absorbents  of  the  limbs  unaccountably  make  its 
way  into  the  veins.”* 

9.  LYMPHATIC  VESSELS  WHICH  THE  THORACIC  DUCT  DIRECTLY  RE- 
CEIVES. 

Several  branches  of  lymphatics  from  the  liver,  and  the 
glands  surrounding  the  cseliac  artery,  have  been  already 
described. 

The  intercostal  lymphatics  are  distributed  to  the  mus- 
cles of  the  thorax  and  the  intercostals ; they  communi- 
cate with  some  glands  found  between  the  external  and 
internal  intercostal  planes  of  the  muscles.  On  the  sides 
of  the  vertebrae,  these  vessels  unite  with  others  which  pro- 
ceed from  the  spinal  canal  and  the  muscles  of  the  back, 
then  spread  out  into  a plexus  before  the  vertebral  col- 
umn. From  thence  they  descend  and  open  into  the 
thoracic  duct. 


10.  LYMPHATIC  VESSELS  OF  THE  LUNGS. 

The  lymphatics  of  the  lungs  are  distributed  upon  their 
surface  in  a series  of  areolae  of  various  forms,  more  com- 
monly hexagonal,  and  unite  into  a number  of  trunks  which 


* Outlines  of  Human  Physiology,  by  Herbert  Mato,  Professor  of  Anat. 
King’s  College,  London. 


LYMPHATIC  SYSTEM. 


39 


enter  the  glands,  with  which  the  bronchus  is  surrounded 
at  its  entrance  into  that  organ.  The  deep  lymphatics 
occupy  the  whole  tissue  of  the  lungs,  communicate  with 
the  superficial,  unite  into  the  bronchial  glands,  and  ascend 
upon  the  trachea. 

From  a large  bronchial  gland,  which  is  found  in  the 
angle  formed  by  the  division  of  the  trachea,  there  issue 
several  lymphatic  branches,  which  ascend  upon  the  tra- 
chea, and,  traversing  some  glands,  unite  and  open  into  the 
right  great  lymphatic  vessel.  Others  traverse  glands  upon 
the  trachea,  under  the  thyroid  gland,  and  collect  into  two 
trunks,  which  incline  obliquely  to  the  left,  behind  the  inter- 
nal jugular  vein,  to  discharge  themselves  into  the  thoracic 
duct. 

11.  SUBSTERNAL,  DIAPHRAGMATIC,  CARDIAC,  THYMIC,  AND  CESOPHA- 
GEAL  LYMPHATIC  VESSELS. 

The  substernal  lymphatics  commence  from  the  upper 
part  of  the  parietes  of  the  abdomen  ; they  enter  the  tho- 
rax between  the  ensiform  cartilage  and  the  diaphragm, 
ascend  behind  the  sternum,  traverse  some  glands,  and  form 
some  meshes,  which  unite  into  trunks,  one  of  which  com- 
municates with  the  inferior  jugular  glands,  and  terminates 
in  the  thoracic  duct.  The  others  open  on  the  right  side 
into  the  subclavian  and  internal  jugular  veins. 

The  lymphatics  of  the  diaphragm  are  distributed  on  its 
convex  surface,  and  unite  with  the  intercostal  and  hepatic 
lymphatics,  then  proceed  through  the  inferior  glands  of 
the  mediastinum,  and  join  the  preceding  behind  the 
sternum. 

The  lymphatics  of  the  pericardium  and  thymus  are  a 
numerous  set  of  reticulated  vessels,  which  are  intimately 
connected  with  the  substernal  and  pulmonary  lympha- 
tics. 


40 


LYMPHATIC  SYSTEM. 


The  lymphatics  of  the  heart  are  distributed  to  the  whole 
surface  ; the  principal  trunks  following  the  course  of  the 
coronary  vessels.  Some  of  these  trunks  ascend  upon  the 
anterior  part  of  the  aorta,  and  terminate  in  the  thoracic 
duct ; others  pass  obliquely  between  the  aorta  and  pul- 
monary artery,  traverse  some  small  glands,  and  arrive  at 
the  thoracic  duct. 

The  lymphatics  of  the  oesophagus  are  reticulated  around 
that  tube  ; they  unite  with  those  of  the  heart  and  lungs, 
and  terminate  in  the  predorsal  ganglia. 

la,  LYMPHATIC  VESSELS  OF  THE  SUPERIOR  EXTREMITIES. 

The  superficial  lymphatics  of  the  upper  extremities  col- 
lect into  fasciculi  on  the  sides  of  the  fingers,  and  proceed 
over  the  metacarpus  to  the  posterior  surface  of  the  fore- 
arm, where  their  numbers  are  greatly  increased  by  the 
addition  of  small  vessels  from  that  part  of  the  extremity. 
Near  the  elbow  joint  the  lymphatics  are  very  distinct ; and, 
upon  the  anterior  surface  of  the  fore-arm,  they  unite  with 
others,  which  arrive  from  the  fingers  and  palm  of  the 
hand.  They  then  ascend  on  the  fore  and  inner  part  of  the 
arm,  and,  becoming  large  and  numerous,  terminate  in  the 
axillary  and  subclavian  glands. 

Some  of  the  brachial  lymphatics  pursue  the  course  of  the 
cephalic  vein,  and  unite  with  some  reticulated  vessels  and 
glands  under  the  clavicle. 

The  deep  lyrnfliatics  of  the  upper  extremities  constantly 
accompany  the  arteries  which  are  distributed  to  these  parts, 
and  terminate  in  the  axillary  glands. 


LYMPHATIC  SYSTEM. 


41 


13,  LYMPHATIC  VESSELS  OF  THE  ANTERIOR  PARIETES  OF  THE  THO- 

RAX. 

The  lymphatics  of  the  anterior  part  of  the  thorax  com- 
mence immediately  under  the  integuments,  and,  proceed- 
ing upwards  and  outwards,  terminate  in  the  glands  of  the 
axilla. 

Some  of  these  vessels  originate  more  deeply  in  the 
substance  of  the  pectoralis  major,  pectoralis  minor,  and  ser- 
ratus  magnus  muscles,  but  they  have  the  same  termina- 
tion. 

14.  I.YMPHATIC  VESSELS  OF  THE  POSTERIOR  REGION  OF  THE  NECK 

AND  THORAX. 

The  lymphatics  of  the  neck  commence  in  the  cellular 
tissue,  towards  the  occiput,  and  upon  the  spinous  processes 
of  the  neck ; they  descend  outwardly  in  the  direction  of 
the  fibres  of  the  trapezius,  and  unite  with  the  anterior 
thoracic,  and  dorsal  lymphatics  in  the  axilla. 

The  lymphatics  of  the  hack  commence  in  the  integu- 
ments, and  are  extended  to  the  whole  of  the  muscles 
of  the  back  ; like  the  preceding,  they  terminate  in  the 
axilla. 

15.  LYMPHATIC  VESSELS  OF  THE  AXILLA. 

The  axillary  lymphatics  are  remarkably  reticulated,  in 
consequence  of  their  connection  with  a great  number  of 
glands,  and  with  the  vessels  which  terminate  in  them,  or 
issue  from  them.  The  latter  concentrate  into  three  or  four 
trunks,  which  proceed  round  the  subclavian  vein,  and  open 
intt»  it,  and  into  the  thoracic  duct.  Those  on  the  right 
6 


VOL.  II. 


42 


LYMPHATIC  SYSTEM. 


side  generally  furnish  a trunk,  which  transmits  its  fluid  to 
the  angle  formed  by  the  right  internal  jugular  and  sub- 
clavian veins  ; and  is  named  the  right  great  lymphatic  duct. 
See  Fig.  5,/. 

16.  LYMPHATIC  VESSELS  OF  THE  HEAD  AND  ANTERIOR  PART  OF  THE 

NECK. 

The  epicranial  lymphatics  are  arranged  on  all  sides  be- 
neath the  skin  of  the  cranium,  and  may  be  distinguished 
into  three  orders  of  fasciculi.  The  occipital,  the  temporal, 
and  the  frontal;  all  which  proceed  to  the  glands  of  the 
neck. 

The  lymphatics  of  the  face  follow  the  direction  of 
the  principal  veins,  and  proceed  to  the  subma.villary 
glands. 

The  superficial  lymphatics  of  the  neclc  form  a plexus, 
which  accompanies  the  subcutaneous  veins  of  the  neck  ; 
they  open  into  the  right  great  lymphatic  vessel,  and  the 
thoracic  duct. 

17.  DEEP  LYMPHATIC  VESSELS  OP  THE  HEAD  AND  NECK. 

The  lymphatics  of  the  brain.  Although  the  most 
minute  researches  have  been  made  in  those  parts,  there 
have  been  discovered  a few  lymphatics  only  in  the  dura 
mater. 

The  deep  lymphatics  of  the  tongue,  palate,  nose,  orbits, 
pharynx,  muscles  of  the  face,  etc.  These  absorbents  ac- 
company the  blood  vessels,  and  terminate  in  the  right  and 
left  great  thoracic  ducts. 


LYMPHATIC  SYSTEM. 


43 


THE  OFFICE  OF  LYMPHATIC  VESSELS  AND  THEIR  GLANDS. 

The  most  important  office  of  the  lymphatic  system  is  to 
collect  the  chyle  for  the  supply  of  the  waste  of  the  body, 
during  the  exercise  of  its  several  functions. 

The  lymphatics,  therefore,  take  in  the  fluids,  it  is  sup- 
posed, by  capillary  attraction,  and  afterwards,  by  a con- 
tractile power,  inherent  in  the  vessels,  conduct  their  con- 
tents into  the  mass  of  the  blood.  The  absorbents  also 
have  the  power  of  removing  the  solid  parts  of  tite  body, 
and  by  thus  making  way  for  the  disposition  of  new  matter, 
contribute  to  the  growth  and  renovation  of  the  animal 
fabric. 

By  means  of  these  vessels,  on  the  one  hand,  many  con- 
tagious diseases  are  communicated  ; and,  on  the  other 
hand,  diseases  are  removed  ; thus,  when  lymph  is  formed, 
or  pus  collected,  or  blood  effused  in  the  tissue  of  organs, 
the  lymphatics  have  the  power  of  taking  away  the  extra- 
neous or  diseased  matter.  And  even  solid  tumours  often 
are  known  to  disappear  entirely  by  the  action  of  this  sys- 
tem of  vessels.  The  obvious  use  of  the  absorbent  vessels 
is  to  convey  the  lymph  and  the  chyle  into  the  venous  sys- 
tem ; the  former,  the  residue  of  nutrition,  and  the  latter, 
the  product  of  digestion. 

I cannot  dismiss  this  subject  without  informing  the  un- 
initiated student,  that  there  is  much  difficulty  in  exhibiting 
the  lymphatics.  They  must  be  injected  with  quicksilver, 
and,  owing  to  the  minuteness  and  delicacy  of  the  vessels, 
it  requires  the  most  acute  sight  of  the  anatomist  to  distin- 
guish, and  to  introduce  an  instrument  into  the  smaller 
branches.  Caution  and  patience,  however,  will  surmount 
this  difficulty  ; and  nothing  will  more  repay  the  trouble,  or 
reflect  more  credit  on  the  skill  of  a practical  anatomist, 
than  a good  preparation  of  the  lacteals,  or  other  lymphatics. 


ART.  VII. 

CHAP.  I. 


NERVOUS  SYSTEM. 

The  nervous  system  is  destined  to  regulate  the  functions 
of  the  animal  economy,  and  to  receive  impressions  of  ex- 
ternal objects,  and  transmit  them  to  the  understanding. 

The  nervous  system  consists  of,  1st,  the  brain  ; 2d,  the 
medulla  oblongata ; 3d,  the  spinal  marrow ; 4th,  the  nerves ; 
5th,  the  ganglia. 

GENERAL  DIVISIONS  OF  THE  NERVOUS  SYSTEM. 

There  are  two  general  departments,  essentially  distinct 
from  each  other,  to  which  the  nervous  system  may  be 
referred  ; the  1st  department  consists  of  the  brain  and  its 
dependencies,  the  2d,  of  the  ganglia  and  their  nervous 
radiations.  The  first  department  appertains  particularly 
to  animal  life  ; on  the  one  hand  it  is  the  agent  which 
transmits  impressions  calculated  to  produce  sensations  ; 
on  the  other  hand  it  serves  to  convey  the  volitions  to 
those  organs  which  receive  them.  The  second  department 
is  almost  invariably  distributed  to  the  organs  of  digestion, 


NERVOUS  SYSTEM. 


45 


of  circulation,  respiration,  and  the  secretions,  and  belongs 
in  a more  particular  manner  to  the  internal  organs,  where 
it  acts  a more  obscure  part  than  the  preceding.  The  two 
departments  frequently  communicate  with  each  other,  but 
there  is  a sufficiently  distinctive  line  to  establish  their  dif- 
ference ; as  a simple  exposition  of  each  will  sufficiently 
demonstrate. 


1.  THE  CEKEBRAL  DEPARTMENT  OF  THE  NERVOUS  SYSTEM. 

This  department  of  the  nervous  system,  like  all  organs 
of  animal  life,  is  exactly  symmetrical.  The  nerves  com- 
mence alike  from  each  side  of  the  brain  and  spinal  cord  : 
hence  the  appellation  of  pair  of  nerves,  by  which  the 
double  corresponding  trunk  is  described.  This  is  a term 
which  we  cannot  apply  to  the  irregularly  distributed  gan- 
glionic department. 

Each  department  of  the  nervous  system  receives  im- 
pressions of  objects,  and  transmits  them  to  the  sensorium ; 
and  these  impressions  or  affections  of  the  nerves,  accom- 
panied by  consciousness,  bear  the  name  of  sensation. 
The  nerves,  which  constitute  the  immediate  instruments 
of  sensation,  are  of  different  kinds,  and  are  distributed  in 
different  proportions  in  the  various  organs  of  the  body ; 
most  of  them  are  capable  of  being  excited  by  agents  both 
from  without  and  from  within,  and  the  impressions  they 
receive  are  transmitted  to  the  brain,  their  common  centre, 
and  frequently  to  the  other  organs  with  which  they  are 
connected.  That  the  nerves  are  truly  the  organs  of  sen- 
sation cannot  be  disputed  ; for  sensation  is  found  to  be 
most  acute  in  those  parts  which  are  furnished  with  most 
nerves,  and  the  sensation  ceases  when  the  nerves  are  de- 
stroyed. When  the  nerve  is  stimulated,  the  muscle  which 

I , 


46 


NERVOUS  SYSTEM. 


it  supplies  is  convulsed  ; when  it  is  tied,  compressed,  or 
divided,  palsy  of  the  muscle  ensues. 

My  present  arrangement  of  the  departments  of  the 
nervous  system,  is  chiefly  founded  on  the  anatomy  and 
distribution  of  the  nerves.  And  here  science  must  ac- 
knowledge its  obligation  to  Sir  Charles  Bell,  for  his 
important  discoveries,  relative  to  the  functions  of  the 
nerves.  So  that,  by  the  operation  of  new  views,  many 
formerly  received  opinions  must  be  reformed,  or  altogether 
expunged.  As  I proceed,  therefore,  in  the  work,  I shall 
endeavor  to  demonstrate,  from  anatomical  and  physiologi- 
cal frets,  that  every  part  of  the  system  has  its  peculiar 
endowment  of  nervous  matter,  fitting  it  for  the  peculiar 
function  it  has  to  perform.  For  example,  it  is  necessary 
to  distinguish  nerves  into  sensitive,  motive,  compound  and 
organic,  and  in  addition  to  the  limited  number  of  senses, 
usually  reckoned  in  the  human  subject,  there  are  other  in- 
ward organs  of  sensation,  which  will  subsequently  be  de- 
scribed, which  have  distinct  functions,  and  depend  on  as 
distinct  departments  of  the  nervous  system,  as  either  see- 
ing, hearing,  or  touch. 

I shall  now  claim  the  attention  of  the  reader  to  the 
general  distribution  of  the  nervous  system. 

The  brain  appears  to  be  the  most  remarkable  part  of 
the  nervous  system,  since  all  intellectual  phenomena  must 
be  referred  to  the  cerebral  mass.  This  organ  furnishes 
generally  the  motive  for  all  our  actions  upon  exterior 
bodies,  exerts  a greater  or  less  influence  upon  all  the  pro- 
perties of  life,  establishes  an  active  relation  amongst  the 
different  organs,  and  is  the  principal  agent  of  sympathies. 
It  is,  moreover,  in  a sensible  relation  with  the  objects  with 
which  we  are  surrounded. 

There  are  two  orders  of  the  cerebral  department  of 
nerves  ; the  1st  constitutes  the  nerves  of  sensation  ; the 
2d,  the  nerves  of  motion. 


NERVOUS  SYSTE3I. 


47 


The  nerves  of  sensation  of  the  first  order,  which  are 
immediately  connected  with  the  brain,  are  endowed  with 
particular  properties,  which  adapt  them  to  the  impression 
of  special  bodies  ; namely,  the  first  pair  of  nerves  perceives 
odours,  the  second  light,  the  eighth  sound  ; and  the  lin- 
gual branch  of  the  inferior  maxillary  nerve  distinguishes 
the  taste  and  flavor  of  bodies.  The  special  senses,  how- 
ever, I shall  hereafter  more  particularly  refer  to. 

The  medullary  column,  or  spinal  marrow,  appears  next 
in  importance  to  the  brain.  It  is  an  irregularly  cylindrical 
prolongation  of  the  brain  ; it  is  not  like  the  Grecian  shaft, 
a simple  column,  but  like  the  Gothic,  a compound  column, 
having  several  shafts  combined.  In  other  words,  the  spinal 
marrow  is  composed  of  four  parts  or  cords,  two  on  each 
side,  which  are  united  the  whole  length.  From  the  ante- 
rior cord,  of  each  side  of  the  column,  issue  the  nerves  of 
motion  ; from  the  posterior  cords,  the  nerves  of  sensation. 
There  is  another  column,  which  is  only  continued  the 
length  of  the  medulla  oblongata,  from  which  the  respirato- 
ry nerves  take  their  origin. 

The  spinal  nerves  are  perfectly  regular  in  their  deriva- 
tion and  distribution.  There  are  thirty,  or  thirtytwo,  on 
each  side  ; this  variation  in  the  statement  of  the  number 
depends  On  the  method  of  reckoning.  Each  nerve  com- 
mences by  two  distinct  roots  ; Fig.  12,  the  one,  c,  proceeding 


48 


NERVOUS  SYSTEM. 


from  the  anterior  ; the  other,  h,  from  the  posterior  division 
of,  a,  the  medullary  column  ; and  each  of  these  roots  is 
composed  of  a number  of  small  filaments,  which,  imme- 
diately after  their  origin,  approach  each  other ; the  poste- 
rior filaments  form,  d,  a ganglion,  and  then  join  the  an- 
terior to  form,  e,  a spinal  nerve : each  nervous  filament 
must  be  considered  as  continuing  distinct  to  its  ultimate 
destination,  though,  by  the  union  of  the  anterior  and  pos- 
terior, the  several  spinal  nerves  possess  the  double  pro- 
perty of  conveying  sensation,  and  producing  motion. 
There  are  other  nerves  of  the  fifth,  sixth,  and  ninth, 
which  are  distributed  separately,  and  are  solely  motive 
nerves,  but  the  fifth  nerve  of  the  encephalon  is  like  the 
spinal  nerves,  in  having  a double  derivation,  and  a two- 
fold function  of  sense  and  motion.  Sir  Charles  Bell 
performed  numerous  experiments  to  prove  the  correct- 
ness of  his  theory,  and  these  experiments  have  been 
repeated  on  the  Continent  by  Magendie  and  others, 
who  have  been  perfectly  satisfied  with  the  accuracy  of 


NERVOUS  SYSTEM. 


49 


his  conclusions.*  It  must,  therefore,  now  be  considered 
as  an  established  fact,  acknowledged  by  all  anatomists,  that 
the  nerves,  proceeding  from  the  anterior  cord  of  the 
spinal  marrow,  bestow  the  power  of  muscular  motion  ; 
and  that  those  which  proceed  from  the  posterior  part  of 
the  medullary  column,  produce  sensation.  When,  for  in- 
stance, the  roots  of  the  anterior  nerves  of  the  leg  are 
divided,  the  animal  loses  all  the  power  of  moving  the 
leg,  although  the  limb  retains  its  sensibility ; but,  if  the 
roots  of  the  posterior  nerves  are  cut,  the  power  of  motion 
continues,  though  sensibility  is  destroyed.  The  experi- 
ments have  been  repeated  and  varied,  yet  with  similar  re- 
sults. Thus,  on  the  posterior  part  of  the  spinal  cord  being 
irritated  with  a pointed  instrument,  the  animal  immediately 
manifested  signs  of  pain  ; but  no  apparent  effect  was  pro- 
duced by  irritating  the  anterior  part.  Every  muscle,  then, 
has  two  distinct  orders  of  nerves  ; the  one  a motive,  and 
the  other  a sensitive  ; and  nerves  of  each  of  these  orders 
are  distributed  to  every  muscular  fibre. 

It  requires,  therefore,  for  the  full  operation  of  muscular 
power,  two  different  orders  of  filaments,  and  these  estab- 
lish a circle  between  the  sensorium  and  the  muscle ; so 
that  the  nerves  of  the  one  order  carry  the  influence  of  the 
will  towards  the  muscles,  which  nerves  have  no  power  of 
transmitting  an  impression  back  again  to  the  brain.  The 
nerves  of  the  other  order  connect  the  muscles  with  the 
brain,  by  acting  as  a sensitive  agent  in  conveying  the  im- 
pression of  the  condition  of  the  muscle  to  the  common 
sensorium ; but  the  last  mentioned  nerves  have  no  opera- 
tion in  a direction  from  the  brain  to  the  muscle,  and,  in 
consequence,  do  not  excite  the  muscle  however  irritated. 

We  find,  however,  that  the  brain  and  medulla  spinalis, 

'^For  details,  I refer  to  the  papers  of  Sir  Charles  Bell,  in  the  Philo. 
Transac.  of  the  Royal  Society. 

7 


von.  II. 


50 


NERVOUS  SYSTEM. 


as  also  the  nerves  communicating  with  them,  are  endowed 
with  different  properties  ; the  common  design  of  which  is 
to  give  us  correct  intelligence  of  the  relative  condition  of 
our  existence.  The  assemblage  of  these  different  parts 
has,  consequently,  with  propriety,  been  called  the  ner- 
vous DEPARTMENT  OF  EXTERNAL  LIFE,  Of  of  animal  life. 
AVhen  the  functions  of  this  part  of  the  nervous  system  are 
suspended,  as  by  a fit  of  apoplexy,  the  individual  is  de- 
prived of  feeling,  and  is  perfectly  insensible  to  every  sur- 
rounding object. 

It  has  already  been  observed,  that  these  nerves  are  en- 
dowed with  two  properties,  viz. : sensibility,  and  vis-mo- 
trix ; hence,  it  follows,  that  there  must  be  nerves  of 
sensation  and  motion.  And  physiological  experiments, 
and  the  observations  drawn  from  pathological  anatomy, 
evidently  prove,  that  sensation  resides  in  the  nervous  fila- 
ments, connected  with  the  posterior  column  of  the  medulla 
spinalis  ; and  motion  in  those  which  are  extended  from  the 
anterior  column. 

As  general  corollaries,  the  nerves  of  sensation  receive 
the  impressions  which  external  agents  produce  upon  us, 
and  transmit  them  to  the  brain.  If  a ligature  be  applied 
around  a nerve,  or  if  the  nerve  be  cut  transversely,  we  find 
that  sensation  is  totally  destroyed  in  that  part  to  which 
the  nerve  is  distributed,  because  the  brain  is  not  in  direct 
communication  with  it.  “ The  brain,  therefore,  is  the 
only  organ  that  enables  us  to  appreciate  the  objects  which 
surround  us  ; the  senses  being  its  advanced  guards,  and 
the  nerves  its  media  of  communication.” 

1.  The  senses  receive  impressions. 

2.  The  nerves  convey  impressions  to  the  brain. 

3.  The  brain  perceives  and  judges,  according  as  they 
appear  useful,  agreeable,  or  hurtful. 

In  conclusion  it  appears,  that,  without  the  due  functions 
of  the  brain,  we  should  neither  possess  external  sensation, 


NERVOUS  SYSTEM. 


51 


nor  be  competent  to  execute  any  voluntary  movement ; 
consequently,  it  has  been  said,  with  much  truth,  that  the 
nervous  system  is,  in  fact,  all  the  animal;*  the  other  sys- 
tems being  vegetative  and  automatic,  and  existing  only  to 
nourish  and  defend  it.  Besides  the  properties  of  sensation 
and  volition,  which  are  common  to  other  animals,  man  is 
distinguished  from  them  by  that  faculty  which  he  possesses 
from  the  Creator,  of  being  able,  by  means  of  his  nervous 
system,  to  compare,  associate,  and  judge  of  the  impressions 
which  he  does  or  has  received,  and  to  deduce  from  them 
the  greatest  consequences. 

Possessing  a faculty  which  constitutes  the  most  beauti- 
ful and  most  noble  attribute  of  our  species,  nature  also 
ordained  that  its  functions  should  correspond  with  the  de- 
gree of  perfection  and  extension  of  the  cerebral  mass.  A 
deficiency  in  the  general  conformation  of  the  brain,  the 
slight  developement  of  some  of  its  parts,  and  the  evident 
or  obscure  alteration  occurring  in  its  structure,  are  so 
many  causes  capable  of  deranging  the  whole  or  part  of  the 
intellectual  faculties  of  man.f  Anatomists  and  physiolo- 
gists have  failed  in  the  attempt  to  trace  the  precise  differ- 
ences between  the  organization  of  the  idiot  and  another 
man  ; though  there  is  no  doubt  that  the  defect  exists  in  the 
organization  of  the  brain,  since  an  idiot  possesses  a soul  in 
common  with  another  man. 

CEREBRAL  DEPARTMENT  OF  THE  NERVOUS  SYSTEM. 

THE  BRAIN  IN  GENERAL. 

The  brain  is  that  mass  which  fills  the  cavity  of  the  skull. 
It  is  distinguished  by  its  divisions  into  the  cerebrum. 


Baron  Cuvier. 


t Manec. 


52 


NERVOUS  SYSTEM. 


the  cerebellum,  the  pons  varolii,  and  the  medulla  oblon- 
gata, all  of  which,  in  the  adult,  weigh  about  three  pounds  ; 
occasionally  the  brain  is  found  to  exceed  this  weight  by 
several  ounces,  according  to  the  size  of  the  head.  In  the 
dimensions  of  the  brain  there  is  a great  difference  in  dif- 
ferent individuals.  The  volume  is  generally  in  proportion 
to  the  mental  capacity.  Let  us  not  suppose,  however, 
that  every  person  having  a large  head  is  necessarily  a per- 
son of  superior  intelligence,  for  there  are  many  causes 
of  an  augmentation  of  the  head  besides  the  size  of  the 
brain. 

The  color  of  the  brain  varies  in  different  individuals  and 
at  different  ages  ; the  color  probably  depending  on  the 
quantity  of  blood  sent  to  it : hence,  it  has  a redder  hue  in 
early  than  in  advanced  life,  and  becomes  still  more  deeply 
colored  in  consequence  of  inflammation. 

The  weight  of  the  brain  of  a full  grown  man  is  about 
three  pounds ; that  of  a woman  is  somewhat  less. 

Baron  Wenzel  paid  great  attention  to  this  department 
of  anatomy,  and  has  published  a very  interesting  table,  of 
which  the  subjoined  is  an  extract. 

■) 


NERVOUS  SYSTEM. 


53 


Weight 

Weight 

Weight 

Proportion 

Age. 

of  whole 

of  brain 

of  cere- 

of  brain  to 

brain. 

only. 

bellum. 

cerebellum. 

Grains. 

Grains. 

Grains. 

Male  embryo  of  5 months 

720 

683 

37 

18XX  :1 

Female  embryo  of  8 months 

4960 

4610 

350 

13/^  :1 

Girl  at  birth  .... 

6150 

5700 

450 

12|  • 1 

Girl  at  3 years  old  . . . 

15240 

13380 

1860 

Boy  3 years  .... 

13050 

11490 

1560 

7-57_  . 1 

'156  * ‘ 

Man  18  years  .... 

20940 

18474 

2466 

7M-.  J 

Man  31  years  .... 

24120 

21480 

2700 

8aV 

Man  54  years  .... 

20580 

18060 

2320 

73A  • 1 

* 8 1 * ^ 

Man  63  years  .... 

22500 

19780 

2720 

7 3 7 .1 
'TTB"  • ^ 

Man  72  years  .... 

22620 

20200 

2420 

Man  80  years  .... 

19080 

16500 

2580 

1 

54 


NERVOUS  SYSTEM. 


Fig.  13.  The  left  side 
of  the  brain  and  spinal 
marrow,  shown  by  mak- 
ing a section  of  the  cra- 
nium and  the  spinal  co- 
lumn, and  removing  the 
dura  mater. 

a,  the  convolutions  of 
the  cerebrum. 

b,  the  laminae  of  the 
cerebellum. 

e,  the  pons  varolii. 

g,  the  medulla  oblon- 
gata. 

c,  d,  f,  the  medulla 
spinalis,  extending  from 
the  first  cervical  to  the 
first  lumbar  vertebra,  and 
terminating  in  the  cauda 
equina. 

The  cerebrum  is  the 
largest  portion  of  the 
brain,  and  occupies  the 
whole  upper  cavity  of 
the  skull.  It  rests  ante- 
riorly, upon  the  arches  of 
the  orbits  ; in  the  centre, 
upon  the  middle  fossae  of 
the  base  of  the  skull ; 
and  posteriorly,  upon  the 
tentorium  cerebelli. 


Fig,  13. 


NERVOUS  SYSTEM. 


55 


THE  EXTERIOR  OF  THE  CEREBRUM. 

The  upper  surface  of  the  cerebrum  is  divided  into  two 
parts,  termed  hemispheres,  which  are  separated  by  the  falx 
cerebri. 

The  surface  of  the  cerebrum  in  general,  both  above  and 
below,  is  intersected  by  deep  fissures  and  eminences, 
which  produce  numerous  turnings  and  windings,  termed 
convolutions ; these  take  a variety  of  directions,  and  differ 
in  extent  in  different  parts  of  the  brain. 

The  convolutions  are  smallest  at  the  anterior  part  of  the 
brain,  larger  posteriorly,  and  are  largest  at  the  superior 
and  central  part  of  the  hemispheres,  where  each  convolu- 
tion is  about  half  an  inch  in  breadth. 

The  number  and  size  of  the  convolutions  vary  exceed- 
ingly in  different  individuals  ; and,  indeed,  they  are  seldom 
found  the  same  in  the  two  hemispheres.  They  extend  in- 
to the  substance  of  the  brain  about  an  inch,  and  are  lined 
by  prolongations  of  the  pia  mater. 

The  lower  surface  of  the  brain  is  formed  into  three  dis- 
tinct regions,  which  are  named  lohes.  The  anterior  lobes 
are  separated  by  the  termination  of  the  grand  division 
which  separates  the  hemispheres.  On  each  of  these  lobes 
we  observe  a deep  rectilinear  groove,  directed  from  behind 
forwards,  for  lodging  the  trunk  of  the  olfactory  nerve. 

The  anterior  and  middle  lobes  are  separated  by  the 
fissura  SYLVii. 

Between  these  interlobular  fissures,  is  the  union  or  com- 
missure  of  the  optic  nerves.  Behind  this  commissure  is 
the  cineritious  tubercle,  which  forms  the  floor  of  the  third 
ventricle,  and  contains  in  its  centre  a small  white  nucleus. 

From  the  middle  of  this  tubercle,  a sort  of  slender  co- 
nical prolongation,  of  a reddish  color,  descends  obliquely 


56 


NERVOUS  SYSTEM. 


forwards,  named  the  pituitary  stem.*  It  passes  under  the 
commissure  of  the  optic  nerve,  and  terminates  in  a small 
body,  situated  in  the  pituitary  fossa  of  the  sphenoid 
bone. 

The  piturVary  5oc/yf  is  the  small  organ  just  alluded  to. 
It  has  not  the  vascular  structure  peculiar  to  glands,  but  is 
composed  of  two  portions  : the  first  is  of  a grayish  yellow 
color ; the  second  is  soft,  and  impregnated  with  a whitish 
viscid  fluid.  The  pituitary  body,  in  the  adult,  generally 
contains  small  calculus  concretions. 

The  corpora  albicantia,  or  mammalaria,  are  situated  be- 
hind the  cineritious  tubercle ; they  consist  of  two  small 
bodies  of  the  form  and  size  of  peas,  which  are  white  ex- 
ternally, and  of  a gray  color  internally  ; they  are  united  to 
each  other  by  a small  grayish  band,  which  contributes  to 
form  the  floor  of  the  third  ventricle. 


THE  EXTERIOR  OF  THE  CEREBELLUM. 

\ 

The  cerebellum  is  situated  in  the  inferior  fossae  of  the 
occipital  bone,  under  the  posterior  lobes  of  the  cerebrum, 
and  is  separated  from  those  lobes  by  the  tentorium.  It  is 
about  a sixth  part  of  the  size  of  the  cerebrum,  and  has 
been  compared  to  two  depressed  spheroids,  placed  beside 
each  other  on  a horizontal  plane.  These  are  divided  pos- 
teriorly by  the  falx  minor.  The  surface  of  the  cerebellum 
presents  an  assemblage  of  gray  laminae,  over  which  the 
arachnoid  membrane  passes.  Each  lobe  commonly  has 
from  sixty  to  sixtyfive  of  these  laminae.  But,  on  sepa- 
rating these  principal  laminae,  we  perceive  many  other 
smaller,  concealed  in  the  grooves,  and  partly  covering  each 
other. 

• Formerly  denominated  the  infundibulum, 
t Formerly  denominated  the  pituitary  gland. 


NERVOUS  SYSTEM. 


57 


The  upper  surface  of  the  cerebellum  presents,  on  its  fore 
and  middle  part,  an  elongated  eminence,  termed  the  supe- 
rior vermiform  process,  which  is  formed  by  the  reciprocal 
crossing  of  the  laminas,  of  which  the  two  lobes  of  this 
organ  are  composed.  The  whole  of  the  upper  surface  is 
occupied  by  five  fasciculated  lobules,  common  to  both 
lobes,  and  disposed  in  transverse  arched  bands. 

The  lower  surface  of  the  cerebellum  presents  a deep  de- 
pression in  the  middle  line,  named,  the  valley,  in  which  is 
lodged  the  commencement  of  the  spinal  marrow  ; posteri- 
orly, it  is  divided  into  two,  by  a large  eminence,  called  the 
inferior  veriniform  process.  Anteriorly,  it  is  terminated  by 
a narrow  rounded  prolongation,  named  the  mammillary 
eminence  of  the  inferior  vermiform  process. 

The  inferior  part  of  the  cerebellum  presents  a convex 
surface,  on  which  we  may  distinguish  four  lobules,  which 
describe  concentric  arches.  At  the  outer  side  of  the  first 
lobule  is  a small  foliated  tuft,  distinguished  by  the  small- 
ness of  its  laminae,  named,  the  lobule  of  the  par  vagum. 

THE  EXTERIOR  OF  THE  PONS  VAROLII.* 

The  ])ons  varolii  forms  as  it  were  the  centre  of  the  brain, 
and  of  which  it  weighs  only  the  sixtieth  part.  It  is  placed 
between  the  cerebrum  and  cerebellum,  and  is  formed  by 
processes  from  them,  termed  their  crura. 

The  anterior  surface  of  the  pons  varolii  is  named,  by 
Gall,  the  commissure  of  the  cerebellum.  Along  the  medi- 
an line  we  observe  a depression  occasioned  by  the  situation 
of  the  basilar  artery. 

The  posterior  surface  of  the  pons  varolii  presents,  on 
its  upper  part,  four  tubercles,  which  are  white  externally, 

^ Tuber  annulare,  or  nodus  cerebri. 

8 


VOL.  II. 


58 


NERVOUS  SYSTEM. 


and  gray  internally  ; these  are  termed  the  tubercula  quadra- 
gemina.  The  two  upper  are  named  the  nates,  the  two 
lower  the  testes.  The  pineal  body  corresponds  to  the  point 
of  intersection  of  the  two  grooves  which  separate  the  tu- 
bercles. Behind  the  tubercula  quadragemina  is  a pulpy 
lamina,  of  a grayish  color,  which  ascends  towards  the  cere- 
bellum, called  the  vahula  vieussenu.  Behind  the  point 
where  it  leaves  the  pons  varolii,  we  may  observe  an 
aperture,  which  is  the  posterior  orifice  of  the  aqueduct  of 
SYLVIUS,  by  which  the  third  and  fourth  ventricles  commu- 
nicate across  the  substance  of  the  pons  varolii.  Farther 
down,  is  a slightly  e.xcavated  surface,  which  forms  the  ante- 
rior part  of  the  fourth  ventricle.  It  is  separated  in  its 
whole  length  by  a narrow  angular  groove,  which  commences 
at  the  aqueduct  of  sylvius,  and  terminates  in  the  spinal 
marrow  opposite  the  atlas.  This  groove  is  called  the  cala- 
mus scriptorius,  from  its  supposed  resemblance  to  a pen. 

THE  MEDULLA  OBLONGATA. 

The  medulla  oblongata  is  that  portion  of  the  cerebral 
formation,  which  extends  from  the  pons  varolii,  to  the 
great  foramen  of  the  occipital  bone. 

Upon  the  surface  of  the  medulla  oblongata  there  are 
two  small  eminences,  which  run  longitudinally,  and  con- 
tiguous to  each  other,  and  from  their  form  have  obtained 
the  name  of  the  corpora  qjyramidalia.  Between  these 
eminences  there  is  a deep  fissure,  into  which  the  blood- 
vessels of  the  pia  mater  penetrate,  to  supply  the  interior  of 
the  medulla. 

On  the  outside  of  the  former  eminences  are  two  others, 
which,  having  somewhat  the  figure  of  olives,  they  are 
termed  the  corpora  olivaria. 


I^ERVOUS  SYSTEM. 


59 


Fig.  M. 


Fig.  14,  the  base  of  the  brain. 

a,  the  anterior  lobes.  b,  the  middle  lobes. 

Tc,  the  posterior  lobes.  n,  the  pituitary  stem. 

c,  the  corpora  albicantia,  or  mammallaria. 

d,  the  pons  varolii. 

h,  h,  the  medulla  oblongata.  The  letters  are  placed  on 
the  corpora  pyramidalia. 

/,  the  cerebellum. 

i,  i,  the  corpora  olivaria. 

e,  the  superior  vermiform  process.  ' 

g,  the  inferior  vermiform  process. 

The  posterior  surface  of  the  medulla  oblongata  is  directly 
continuous  with  the  pons  varolii,  and  contributes  to  form 
the  fourth  ventricle.  On  each  side  of  the  upper  and  back 


60 


NERVOUS  SYSTEM. 


part  of  the  medulla  oblongata,  we  observe  two  whitish 
oblong  eminences,  named  the  corpora  restiformia,  which 
contribute  to  the  formation  of  the  cerebellum. 

THE  MEDULLA  SPINALIS. 

The  medulla  spinalis  or  spinal  marrow  is  a long,  irregu- 
larly cylindrical  cord,  which  extends  within  the  vertebral 
canal,  from  the  great  occipital  foramen,  to  the  second  lum- 
bar vertebra.  Its  weight  is  about  one-twentieth  part  of 
that  of  the  brain. 

The  anterior  surface  of  the  medullary  cord  corresponds 
to  the  bodies  of  the  vertebrae.  A very  deep  and  distinct 
fissure  is  extended  its  whole  length,  dividing  it  into  two 
equal  lateral  portions.  Its  posterior  surface  is  also  divided 
by  a similar  median  line,  which  commences  between  the 
two  corpora  restiformia.  By  this  disposition,  the  spinal 
marrow  is  divided  into  a double  cord,  intimately  connected 
in  its  total  extent. 

On  the  posterior  and  anterior  surfaces  of  the  body  of 
the  spinal  cord,  on  each  side,  and  at  some  distance  from 
the  median  groove,  are  collateral  depressed  lines,  in  which 
we  find  the  roots  of  the  spinal  nerves. 

Finally,  it  presents  a great  number  of  small  transverse 
grooves  particularly  apparent  from  the  last  cervical  to  the 
ninth  dorsal  vertebra. 

The  exterior  of  the  spinal  cord  consists  of  a layer  of 
white  substance,  half  a line  thick,  and  after  immersion  in 
alcohol,  this  peels  readily  into  longitudinal  fibres,  which 
are  separable  into  filaments  that  continually  branch,  and 
thus  attach  themselves  to  those  adjoining. 

Upon  making  a transverse  section  of  the  spinal  cord, 
a thin  curved  layer  of  gray  matter  is  seen  in  each  lateral 


NERVOUS  SYSTEM. 


61 


half,  the  convex  margin  of  which  is  inwards,  and  is  joined 
to  its  fellow  by  a transverse  layer. 

THE  INTERNAL  ORGANIZATION  OF  THE  BRAIN. 

The  brain  is  soft  and  pulpy,  but  its  density  varies  ac- 
cording to  the  age.  In  infancy  it  is  extremely  tender  and 
yielding,  and  it  acquires  firmness  as  the  person  advances 
in  life.  Its  specific  gravity,  in  the  adult,  is  1310.  The 
cerebral  tissue  is  soluble  in  water,  insoluble  in  alcohol  and 
fixed  oils. 


CHEMICAL  ANALYSIS  OF  THE  BRAIN. 

According  to  M.  Vauruelin  there  is  no  difference  of 
composition  in  the  different  parts  of  the  nervous  system  : 
the  analysis  of  the  brain,  of  the  cerebellum,  of  the  spinal 
marrow,  and  the  nerves  gives  the  same  result.  He  found 
in  them  all  the  same  matter,  the  composition  of  which 
is  of  - - , 


Water,  . . . . * . 

80-00 

White  fatty  matter,  . . . 

4-53 

Red  fatty  matter,  . . 

0-70 

Osmazome, 

1-12 

Albumen,  . 

7-00 

Phosphorus, 

1-50 

Sulphur  and  salts,  such  as 

Phosphate  of  potass,  . '] 

“ of  lime,  . . ^ 

> 5-15 

“ of  magnesia,  ) 

The  substance  of  the  brain  presents  two  distinct  modi- 
fications. 


62 


NERVOUS  SYSTEM. 


1st.  The  cortical  or  cmeritious  substance  covering  the 
brain  in  general,  about  the  sixth  of  an  inch  in  thickness  ; 
it  also  enters  deep  between  its  convolutions,  and  is  dis- 
tributed through  difl’erent  parts  of  its  interior.  This  part 
of  the  brain,  when  examined  with  a microscope,  appears 
to  consist  of  minute  molecules,  smaller  than  the  red  parti- 
cles of  the  blood.  They  are  connected  together  by  a 
transparent  tissue,  containing  a serous  fluid,  and  supplied 
with  very  minute  and  infinitely  numerous  blood-vessels. 

2d.  The  meduUarij  or  white  substance  is  firmer  and 
denser  than  the  former  ; its  mass  is  also  much  greater  than 
that  of  the  corticular  substance,  and  is  filled  with  a great 
quantity  of  vascular  ramifications,  which,  on  making  a sec- 
tion of  the  brain,  present  so  many  red  points  with  the 
blood  oozing  from  them. 

All  the  fasciculi  of  medullary  fibres  placed  in  the  medulla 
oblongata,  appear  to  expand  so  as  to  form  the  mass  of  the 
brain  ; and  more  especially  to  originate  from  the  pyramidal 
and  olivary  eminences.  The  fibres  of  the  former  on  the 
one  side  proceed  to  the  opposite  side,  crossing  each  other, 
and  progressively  acquiring  more  volume  as  they  ascend  to 
form  the  cerebral  mass. 

These  two  substances  of  the  brain  do  not  constitute  one 
homogeneous  mass,  but  are  arranged  into  a great  variety 
of  eminences,  cavities,  laminae,  partitions,  etc.  differing  in 
their  color,  consistence,  and  volume.  I shall  now  proceed 
to  demonstrate  the  brain  in  each  of  these  particulars,  not 
by  attempting  to  unfold  the  structure  in  the  manner  of 
Reil  and  Spurzheim,  but  shall  describe  the  several  parts 
as  they  are  exhibited  in  the  recent  and  most  familiar  modes 
of  dissection.* 

The  corpus  collosum  or  commissura  magna  is  the  centre 

" In  order  to  exhibit  the  fibrous  and  larnelated  structure  of  the  brain,  it 
must  be  immersed  for  a requisite  time  in  alcoliol. 


NERVOUS  SYSTEM. 


63 


of  communication  between  the  hemispheres:  it  is  seen, 
without  making  an  incision,  by  merely  separating  these 
hemispheres  with  the  fingers.  It  consists  of  a large  por- 
tion of  medullary  matter,  which  by  transverse  fibres,  in- 
corporates and  unites  the  two  lateral  divisions  of  the  cere- 
brum. 

The  centrum  ovale  is  the  appearance  which  is  exhibited 
when  the  brain  is  cut  horizontally,  on  the  level  of  the  cor- 
pus callosum ; the  corpus  callosum  constitutes  the  centre 
of  the  great  medullary  mass  of  the  cerebrum,  and  the  cor- 
tical substance,  being  on  its  edges,  forms  the  central  white 
mass  into  an  irregular  oval. 

In  the  middle  of  the  corpus  callosum  there  is  a longitu- 
dinal line  called  the  raphe ; it  has  a medullary  cord  on 
each  side,  from  which  numerous  short  transverse  lines  pro- 
ceed, termed  the  transverse  medullary  traces. 


64 


NERVOUS  SYSTEM. 


Fig.  15. 


Fig.  15,  a transverse  section  of  the  brain,  upon  a level 
with  the  corpus  callosum. 

a,  a,  a,  the  corticular  part  of  the  convolutions,  with 
the  fissures  between  them. 

b,  b,  the  medullary  part,  forming  the  centrum  ovale  of 

ViEUSSENS. 

c,  the  raphe,  on  each  side  of  which  are  longitudinal  ele-, 
vated  lines,  and  transverse  striae. 

In  the  substance  of  the  brain  we  find  four  cavities 
termed  the  ventricles. 

There  are  two  lateral  ventricles,  one  is  situated  in  the 
central  part  of  each  hemisphere.  They  are  of  an  irregular- 
form,  lying  under  the  centrum  ovale,  and  each  having 
three  winding  prolongations  termed  cornua.  The  anterior 
cornua  are  separated  from  each  other  by  a partition,  called 


NERVOUS  SYSTE3I. 


65 


the  septum  lucidum;  the  posterior  cornua  are  at  a consid- 
erable distance  from  each  other,  but  as  they  curve  inwardly 
and  dip  into  the  middle  lobes  of  the  brain,  they  approach 
nearer  at  their  pointed  extremities.  The  cavities  of  these 
ventricles  are  principally  situated  between  the  corpus  cal- 
losum and  the  corpora  striata,  and  thalami  nervorum  opti- 
corum. 

Fig.  16. 


Fig.  16,  a horizontal  section  of  the  cerebrum,  a little 
deeper  than  in  Fig.  15. 

a,  a,  the  anterior  cornua  of  the  lateral  ventricles. 
h,  b,  the  posterior  cornua, 
c,  c,  the  corpora  striata. 

e,  e,  the  optic  thalami. 

f,  d,  the  septum  lucidum,  showing  the  fissure  termed  the 
fifth  ventricle  and  extending  between  the  two  letters, — 

g,  g,  the  choroid  plexus. 

VOL.  II.  9 


66 


NERVOUS  SYSTEM. 


Tlie  lateral  ventricles  communicate  with  each  other,  and 
with  the  third  ventricle  by  an  opening,  named  the  foramen 
MONRoiANUM,  Under  the  arch  of  the  fornix. 

The  septum  lucidum,  or  septum  of  the  ventricles,  is  a soft 
and  fhin  medullary  production,  which  is  continuous  above 
with  the  middle  part  of  the  inferior  surface  of  the  corpus 
callosum  ; inferiorly,  it  is  connected  with  the  fornix,  and 
forms  a distinct  partition  between  the  lateral  ventricles.  It 
is  composed  of  two  laminae  with  a narrow  cavity  between 
them,  which  has  been  considered  by  Cuvier  as  n fifth  ven- 
tricle. 


PARTS  OBSERVED  IN  THE  LATERAL  VENTRICLES. 

The  fornix  is  a flat  triangular  medullary  body,  having  its 
upper  surface  contiguous  to  the  corpus  callosum,  and  sup- 
porting the  septum  lucidum.  Its  lower  surface  is  situated 
upon  the  choriod  plexus  and  optic  thalami ; one  of  the  an- 
gles is  forward  and  the  other  two  are  towards  the  back  part; 
and  the  foramen  of  Monro  is  under  the  most  anterior  part. 

The  posterior  angles  of  the  fornix  have  a bifurcated  pro- 
longation ; one  of  the  branches  of  which  is  short,  and  loses 
itself  in  the  white  layer  of  the  cornua  ammonis.  The 
other,  which  is  long,  is  named  the  corpus  fimbriatum ; it  is 
flattened,  and  extends  into  the  lowest  part  of  the  lateral 
ventricle. 

The  corpora  fimbriata,  or  tcenia  hippocampi,  are  the 
plaiting  of  the  margin  of  the  processes  of  the  fornix, 
which  pass  into  the  inferior  cornua  of  the  ventricles. 

The  pes  hippocampi,  or  cornu  ammonis,  is  found  at  the 
termination  of  the  line  called  ta3nia  hippocampi,  at  the 
posterior  prolongation  of  the  fornix. 

psalterium,  or  lyra,  consists  of  numerous  transverse 
lines,  which  are  impressed  upon  the  under  surface  of  the 
posterior  part  of  the  body  of  the  fornix. 


NERVOUS  SYSTEM. 


67 


The  choroid  plexus  is  displayed  by  dividing  the  body  of 
the  fornix  and  inverting  it.  This  plexus  consists  of  a 
spongy  mass  of  tortuous  vessels  and  reddish  granulations, 
covering  the  optic  thalami  and  corpora  striata,  and  contin- 
ued into  the  inferior  cornua  of  the  lateral  ventricles.  The 
plexus  of  each  side  is  connected  to  its  fellow  by  the  velum 
interpositum,  a vascular  membrane  which  passes  under  the 
fornix,  and  lies  on  the  third  ventricle  and  corpora  quadrige- 
mina.  The  plexus  returns  its  blood  by  two  parallel 
branches,  termed  the  venae  galeni  ; these  veins  run  back- 
wards, and  enter  the  sinus  rectus. 

The  corpora  striata  are  two  smooth  cineritious  pyriform 
eminences,  broad  before  and  contracted  behind  ; they  are 
situated  in  the  fore  part  of  the  lateral  ventricle.  Their 
color  at  the  outside  is  gray,  somewhat  tinged  with  brown ; 
but  on  cutting  them  obliquely,  cineritious  and  medullary 
substances  are  seen  disposed  in  their  interior,  in  alternate 
streaks.  The  white  fibres  may  be  traced  to  the  original 
fasciculi  of  the  corpora  olivaria. 

The  optic  thalami  are  two  oval  medullary  eminences, 
placed  by  the  side  of  each  other,  between  the  diverging 
extremities  of  the  corpora  striata ; their  upper  surface  forms 
a part  of  the  floor  of  the  ventricles ; their  lower  surface 
presents,  externally,  two  prominences.  The  corpora  geni- 
culata,  which  furnish  several  filaments  to  the  optic  nerve, 
may  be  seen  at  the  inferior  surface  of  the  cerebrum. 

The  commissura  mollis  is  a band  of  a gray  color,  connect- 
ing the  convex  surfaces  of  the  optic  thalami. 

The  tcenia  semicircularis  is  a line  of  white  semitranspa- 
rent substance,  running  between  the  convex  surface  of  the 
optic  thalami  and  the  corpora  striata. 


68 


NERVOUS  SYSTEM. 


Fig.  17. 


Fig.  17.  a,  a,  the  optic  thalami,  on  the  outer  margin  of 
which  is  seen  the  taenia  semicircularis. 

e,  e,  the  corpora  striata. 

d,  the  cavity  (termed  the  fifth  ventricle)  which  exists  be- 
tween the  two  laminiB  of  the  septum  lucidum. 

c,  the  anterior  pillars  of  the  fornix  cut  off  at  their  base. 

b,  the  fornix  turned  back,  shewing  on  its  inferior  surface — 

f,  the  lyra. 

g,  the  taenia  semicircularis  or  white  line  separating  the 
surface  of  the  corpora  striata  and  the  thalami. 

The  commissura  anterior  cerebri  is  a short  cylindrical 
medullary  cord,  extending  transversely  between  the  cor- 
pora striata,  immediately  under  the  anterior  prolongations 
of  the  fornix. 

The  vulva  is  a small  aperture  formed  by  the  anterior  pro- 
longations of  the  fornix,  bifurcating  and  adhering  on  each 


NERVOUS  SYSTEM. 


69 


side,  between  the  corpus  striatum,  and  the  thalamus  nervi 
optici.  This  aperture  is  the  part  by  which  the  three  ven- 
tricles communicate. 

The  third  ventricle  is  situated  between  the  optic  thalami 
and  the  crura  cerebri ; it  is  a deep  fissure.  At  the  upper 
and  fore  part  it  communicates  with  the  lateral  ventricles, 
and,  at  the  lower  part,  with  the  infundibulum.  The  latter 
opening  is  called  iter  ad  infundibulum.  A canal  extends 
backwards  under  the  tubercula  quadrigemina,  into  the 
fourth  ventricle.  This  passage  is  called  the  aqueduct  of 

SYLVIUS. 

The  anus,  or  foramen  commune  posterius,  is  situated  be- 
hind the  commissure  of  the  optic  thalami,  and  is  the  ante- 
rior aperture  of  the  aqueduct  of  sylvius. 

The  commissura  posterior  is  a transverse  cord  at  the  pos- 
terior part  of  the  third  ventricle. 

The  pineal  gland  is  situated  beneath  and  behind  the 
fornix,  and  above  the  tubercula  quadrigemina  ; it  is  a small 
grayish  body  of  the  size  of  a pea ; it  is  perfectly  isolated 
from  the  cerebral  substance,  excepting  at  the  fore  part, 
where  it  is  connected  to  the  optic  thalami  by  two  medul- 
lary cords,  — the  peduncles  of  the  pineal  gland.  In  the 
adult  it  contains  little  calculi,  very  hard  and  resembling 
grains  of  coarse  sand. 


THE  INTERNAL  STRUCTURE  OF  THE  CEREBELLUM. 

The  substance  of  the  cerebellum  is  composed  of  cineri- 
tious  and  medullary  matter,  as  in  the  cerebrum.  The  cin- 
eritious,  however,  bears  a much  greater  proportion  in  the 
former  than  in  the  latter. 

The  arbor  vitce  is  a beautiful  tree-like  appearance,  which 
we  observe  on  making  a vertical  section  of  the  cerebellum. 
This  appearance  is  formed  by  the  peculiar  arrangement  of 
medullary  and  cineritious  matter. 


70 


NERVOUS  SYSTEM. 


The  corpora  restiformia  are  processes  of  medullary  mat- 
ter, which  e.xtend  from  the  medulla  oblongata  to  the 
medullary  crura  of  the  cerebellum. 

The  fourth  ventricle  is  the  ventricle  of  the  cerebellum  ; 
tlie  sides  of  this  cavity  are  formed  by  it,  the  anterior  part 
by  the  medulla  oblongata,  and  the  upper  and  back  part  by 
the  valvula  vieussenu. 

The  calamus  scriptorius  is  the  groove  and  its  pointed  ter- 
mination in  the  fourth  vetricle,  which  vesalius  conceived 
to  have  a great  resemblance  to  a writing  pen. 

The  aqueduct  of  sylvius  enters  the  upper  part  of  this 
ventricle,  and  the  valvula  vieussenii  hangs  over  it. 


Fig.  ]8. 


Fig.  18,  a horizontal  section  of  the  cerebrum  and  an 
oblique  division  of  the  cerebellum. 

a,  the  anterior  part  of  the  corpus  callosum. 


NERVOUS  SYSTEM. 


71 


b,  the  corpus  striatum. 

c,  the  optic  thalamus. 

d,  the  taenia  semicircularis. 

e,  the  anterior  pillars  of  the  fornix  cut  off  at  their  base. 

f,  the  commissure  of  the  optic  thalami. 

g,  the  pineal  gland,  situated  on  the  four  eminences,  term- 
ed the  corpora  quadrigemina. 

h,  valvula  vieussenii. 

~k,  the  arbor  vitae  shewn  by  an  oblique  section  of,  n,  the 
cerebellum. 

Z,  the  fourth  ventricle,  terminating  in, — 

m,  the  calamus  scriptorius. 

71,  the  cerebellum. 

The  arteries  of  the  cerebrum  and  cerebellum  are 
branches  of  the  internal  carotid  and  vertebral  arteries,  from 
the  latter  of  which  arises  the  basilar  artery  ; ramifications 
of  these  vessels  communicate  with  each  other,  and  form, 
what  is  termed,  the  arterial  circle  of  Willis. 

The  spinal  marrow  receives  its  arteries  from  the  verte- 
bral, dorsal,  lumbar,  and  sacral  arteries. 

The  veins  of  the  brain  are  very  delicate  in  their  struc- 
ture ; they  communicate  with  the  sinuses  of  the  dura 
mater,  and  the  sinuses  pour  their  contents  into  the  internal 
jugular  veins. 

The  veins  of  the  spinal  marrow  terminate  in  the  verte- 
bral, dorsal,  lumbar,  and  sacral  veins. 

No  lymphatic  vessels  have  yet  been  discovered  in  the 
brain. 


72 


NERVOUS  SYSTEM. 


Fig.  19. 


Fig.  19,  exhibits  the  brain  placed  on  its  base,  with  a 
vertical  incision  made  through  the  corpus  callosum,  as  far 
as  the  anterior  commissure,  and  continued  posteriorly  to 
the  tubercula  quadrigemina.  The  hemispheres  are  sepa- 
rated from  each  other  and  turned  to  each  side.  The  sep- 
tum lucidum  and  fornix  are  removed.  The  cerebellum, 
in  a similar  manner,  is  divided  as  far  as  the  fourth  ven- 
tricle. 

а,  «,  the  cut  edges  of  the  corpus  callosum. 

б,  h,  h,  b,  the  tubercula  quadrigemina. 

c,  the  pineal  gland. 

d,  medullary  stri®  in  the  fourth  ventricle,  which  form 
the  beginnings  of  the  auditory  nerves. 

e,  the  third  ventricle. 


NERVOUS  SYSTEM. 


73 


/,  part  of  the  pituitary  stem. 

g,  the  medullary  portion  of  the  cerebellum. 

Aj  the  fourth  ventricle. 

i,  the  calamus  scriptorius,  at  the  inferior  part  of  the 
fourth  ventricle. 

Ic,  the  medulla  spinalis. 

l,  the  taenia  semicircularis. 

m,  the  peduncle  of  the  pineal  gland. 

n,  a section  of  the  anterior  commissure  of  the  brain. 

The  brain  is  the  primary  organ  of  sensation  ; the  mind 

is  supposed  to  be  most  immediately  and  intimately  connect- 
ed with  it,  and,  from  observations  and  experiments,  it  is 
found  to  communicate  nervous  influence  to  all  the  other 
parts  of  the  body.  That  the  brain  is  the  organ  of  the 
mind,  is  evident  by  the  connection  between  the  brain  and 
the  organs  of  sense,  by  our  consciousness,  and  by  the 
mental  disturbance  which  ensues  under  disease  of  the 
brain.  In  asserting,  however,  that  the  brain  is  the  organ 
or  instrument  of  the  mind,  it  is  not  intended  to  convey  an 
idea  that  the  mind  is  material,  but  that  the  exercise  of  the 
mental  powers  depend  on  the  living  brain. 


VOL.  II. 


10 


74 


NERVOUS  SYSTEM. 


CHAP.  II. 

THE  MEMBRANOUS  ENVELOPES  OF  THE  BRAIN. 

The  membranes  of  the  brain  are  called  matres  by  the 
ancients,  from  a notion  that  they  gave  origin  to  all  the 
other  membranes  of  the  body  : no  argument  is  required  to 
refute  so  absurd  an  opinion. 

The  membranous  envelopes  of  the  brain  consist  of  the 
dura  mater,  the  tunica  arachnoidea,  and  the  pia  mater. 


1.  THE  DURA  MATER. 

The  dura  mater  is  the  outermost  envelope  of  the  brain  ; 
it  is  common  to  that  organ  and  to  the  skull,  that  is,  it  in- 
closes the  brain  and  its  appendages,  and  performs  the  office 
of  an  internal  periosteum  to  the  cranium. 

This  membrane  is  of  a very  firm  and  compact  texture  ; 
it  is  composed  of  tendinous-like  fibres,  which  have  a glossy, 
semitransparent,  and  pearly  appearance.  It  is  divisible  by 
maceration  into  two  or  more  fibrous  layers. 

The  outer  surface  of  the  dura  mater  adheres  rather 
loosely  to  the  bones  of  the  skull,  and  is  easily  detached 
from  them ; but  at  the  sutures  and  foramina  it  is  more 
firmly  connected  than  elsewhere. 

The  inner  surface  of  the  dura  mater  is  remarkably  smooth, 
and  forms  several  folds,  which  are  named  the  falx  cerebri, 
the  tentorium  cerehelli,  and  Xha  falx  cerehelli. 

The  falx  cerebri  is  a duplicature  or  process  of  the  dura 
mater,  and  has  some  resemblance  in  shape  to  the  blade  of 
a sickle,  from  which  circumstance  it  has  obtained  the  name 
of  falx.  It  separates  the  two  hemispheres  of  the  brain 
from  each  other.  Its  upper  edge,  which  is  extended  from 
the  frontal  ridge  to  the  middle  groove  of  the  occipital  bone. 


NERVOUS  SYSTEM. 


75 


lodges  the  superior  longitudinal  sinus.  Its  lower  edge 
passes  over  the  corpus  callosum,  and  contains  the  inferior 
longitudinal  sinus.  Its  anterior  extremity  is  attached  to 
the  crista  galli ; the  posterior  is  continued  into  the  tento- 
rium, and  contains  the  straight  sinus. 

The  tentorium  cerebelli  is  a membranous  partition  which 
separates  the  cerebrum  from  the  cerebellum.  Like  the  falx 
cerebri,  it  is  in  a continual  state  of  tension.  Its  outer  cir- 
cumference contains  the  lateral  sinus,  and  is  connected  to 
the  edges  of  the  lateral  groove  of  the  occipital  bone.  The 
inner  edge  corresponds  to  the  cerebral  protuberances. 
The  extremities  of  the  tentorium  meet  at  an  acute  angle, 
and  cross  over  each  other,  like  the  letter  X,  to  be  attached 
to  the  clinoid  processes  of  the  sphenoid  bone. 

The  falx  cerebelli  is  a process  of  the  dura  mater,  which 
is  placed  between  the  lobes  of  the  cerebellum,  and  is  ex- 
tended from  the  internal  occipital  protuberance,  to  the 
great  occipital  foramen. 

The  dura  mater  is  evidently  fibrous,  and  its  fibres  are  very 
apparent  in  the  folds  just  mentioned,  and,  in  particular,  at 
the  upper  part  of  the  falx  cerebri.  Some  minute  nervous 
filaments  have  been  discovered  in  the  course  of  the  arteries 
of  the  dura  mater.  The  blood  vessels  are  not  very  numer- 
ous. The  principal  branches  of  the  arteries  are  distributed 
upon  the  external  surface  ; minute  ramifications  only  being 
observed  on  its  inner  surface.  The  smaller  veins  of  this 
membrane  accompany  the  arteries,  the  larger  veins  consti- 
tute the  sinuses  which  I am  about  to  describe. 


SINUSES  OF  THE  DURA  MATER. 

The  sinuses  of  the  dura  mater  are  merely  the  large  veins 
of  the  brain,  which  are  received  into  triangular  canals  of 
the  dura  mater ; they  vary  in  their  dimensions,  and  are  dis- 


76 


NERVOUS  SYSTEM. 


posed  in  a regular  symmetrical  manner.  They  are  formed 
e.xternally  by  the  dura  mater,  and  internally  by  a smooth 
membrane,  similar  to  that  which  is  met  with  in  the  veins. 
As  they  are  constantly  stretched  in  all  point  of  their  ex- 
tent, they  can  neither  change  their  situation  nor  contract 
upon  themselves.  They  are  remarkable  for  having  at  in- 
tervals fibrous  bridles,  which  pass  irregularly  from  side  to 
side  of  the  canal.  All  the  veins  of  the  dura  mater  and  of 
the  brain  pour  their  blood  into  the  sinuses. 

Fig.  20,  a,  a transverse  section  of  the 
superior  longitudinal  sinus. 

b,  a similar  section  of  the  inferior  longi- 
tudinal sinus. 

c,  a portion  of  the  cranium. 

The  superior  longitudinal  sinus  is  a long 

triangular  canal,  which,  commencing  at  the  crista  galla  of 
the  ethmoid  bone,  and  extending  along  the  upper  edge  of 
the  falx  cerebri,  becomes  gradually  larger  in  its  progress, 
and  terminates  in  the  lateral  sinuses. 

The  inferior  longitudinal  sinus  is  much  smaller  than  the 
preceding,  and  is  situated  at  the  inferior  margin  of  the  falx, 
extending  from  its  anterior  third  to  the  tentorium  cerebelli, 
terminating  posteriorly  by  two  branches  in  the  straight  sinus. 

The  torcular  herophili*  is  an  irregular  cavity  situated 
at  the  union  of  the  three  great  folds  of  the  dura  mater  ; it 
presents  six  apertures,  viz. : 1st,  that  of  the  superior  longi- 
tudinal sinus  ; 2d,  two  inferior,  corresponding  to  the  occi- 
pital sinuses ; 3d,  one  anterior  belonging  to  the  straight 
sinus  ; 4th,  two  lateral  openings  on  the  right  and  left  lead- 
inji  into  the  lateral  sinuses. 

The  straight  sinus  is  situated  at  the  base  of  the  falx  ; it 
is  a continuation  of  the  vena  galeni,  and  extends  from 

* The  term  torcular  was  originally  applied,  from  a supposition  that  the 
blood  is  squeezed  in  this  sinus  as  in  a wine  press. 


NERVOUS  SYSTEM. 


77 


the  termination  of  the  inferior  longitudinal  sinus  to  the 
torcular  herophili. 

The  occipital  sinuses  are  situated  on  the  sides  of  the  oc- 
cipital foramen,  and  passing  into  the  falx  cerebelli,  open 
into  the  torcular  herophili. 

The  lateral  sinuses  are  very  large,  and  extend  from  the 
torcular  herophili  to  the  commencement  of  the  jugular 
veins,  occupying  the  lateral  grooves  of  the  occipital  bone, 
as  far  as  the  foramen  lacerum  posterius. 

The  coronary  sinus  surrounds  the  pituitary  fossa ; it  is 
very  small  in  its  whole  course,  and  opens  to  the  right  and 
left  into  the  cavernous  sinuses. 

The  cavernous  sinuses  are  very  broad  and  short ; they 
are  situated  in  the  lateral  grooves  of  the  sphenoid  bone. 
They  commence  beneath  the  anterior  clinoid  processes,  and 
terminate  in  the  inferior  petrous  sinuses.  The  outer  pari- 
etes  of  this  sinus  contain,  in  their  substance,  the  common 
motor,  the  pathetic,  and  ophthalmic  nerves.  The  cavity 
of  the  cavernous  sinus  is  occupied  by  a number  of  reticu- 
lated filaments  ; the  internal  carotid  artery,  and  the  external 
motor  nerve  of  the  eye. 

Beneath  the  pituitary  body  the  two  cavernous  sinuses 
communicate  by  the  sinus  transversalis  sellce  turcicce. 

The  superior  petrous  sinuses  extend  from  the  termination 
of  the  preceding  sinuses,  towards  the  summit  of  the  petrous 
portion  of  the  temporal  bone,  and  open  into  the  lateral 
sinuses. 

The  inferior  petrous  sinuses  extend  from  the  cavernous 
sinuses,  to  the  inferior  edge  of  the  petrous  and  basilary 
processes,  and  terminate  in  the  lateral  sinuses. 

The  anterior  occipital  sinus  forms  a communication  be- 
tween the  two  petrous  sinuses  and  the  cavernous  sinus,  by 
extending  transversely,  at  the  upper  part  of  the  basillary 
process. 


78 


NERVOUS  SYSTEM. 


Fig. 21. 


Fig.  21.  A lateral  view  of  the  veins  of  the  processes  of 
the  dura  mater,  termed  the  sinuses. 
a,  the  falx. 

h,  the  tentorium  cerebelli. 

c,  the  superior  longitudinal  sinus. 

d,  the  straight  sinus, 
c,  the  lateral  sinus. 

f,  the  internal  jugular  vein. 

g,  the  inferior  longitudinal  sinus. 

A,  the  occipital  sinus. 

i,  the  vena  galeni. 

A,  the  torcular  herophili. 


2.  THE  ARACHNOID  MEMBRANE. 

The  arachnoid  membrane  is  situated  between  the  dura 
mater  and  pia  mater ; it  has  been  named  arachnoid,  from 


NERVOUS  SYSTEM. 


79 


its  extreme  thinness,  resembling  a spider’s  web  ; it  is  ex- 
tended over  the  convolutions  of  the  cerebrum,  the  cere- 
bellum, and  the  base  of  the  pons  vakolii. 

The  exterior  arachnoid  membrane  does  not  adhere  to  the 
other  membranes  of  the  brain,  for  it  can  be  very  easily 
raised  by  insufflation  with  a blow  pipe ; it  possesses  no  ap- 
parent vascularity,  but  is  constantly  moistened  with  a serous 
fluid,  and  forms  a sheath  or  envelope  for  all  the  nerves  and 
all  the  vessels  which  enter  or  issue  from  the  skull.  This 
membrane  also  passes  downwards  into  the  vertebral  canal, 
around  the  spinal  marrow,  and  furnishes  a conical  sheath 
for  each  of  the  vertebral  nerves. 

The  interior  arachnoid  membrane  is  continuous  with  the 
preceding  ; penetrating  into  the  third  ventricle  by  a small 
oval  opening,  found  between  the  corpus  callosum  and 
tubercula  quadrigemina,  and  lining  the  third  ventricle,  and 
extending  over  the  choroid  plexus,  it  is  continued  over  the 
parietes  of  the  lateral  and  fourth  ventricles,  into  which  it 
passes  through  the  aqueduct  of  sylvius. 


3.  THE  PIA  MATER. 

The  pia  mater  is  the  third  membrane  of  the  brain  ; it  is 
a cellular,  loose,  transparent  web,  in  which  a multitude  of 
blood  vessels,  more  or  less  delicate,  cross  each  other  in  a 
thousand  different  directions,  and  it  is  attached  to  the  sur- 
face of  the  brain  by  the  minute  branches  of  these  vessels, 
which  penetrate  into  the  latter  organ.  It  invests  the  brain 
on  all  sides,  dipping  into  the  convolutions  of  the  hemis- 
pheres, and  covering  the  superior  surface  of  the  corpus 
callosum ; covering  inferiorly  the  base  of  the  brain  and  the 
pons  VAKOLII : it  is  also  reflected  over  the  cerebellum,  and 
sinks  between  its  concentric  laminae. 


80 


NERVOUS  SYSTEM. 


The  pia  mater  penetrates  into  the  third  and  lateral 
ventricles  by  the  great  fissure,  which  is  situated  between 
the  corpus  callosum  and  the  pons  vakolii,  and  by  the 
two  lateral  fissures.  It  forms,  1st,  the  choroid  web,  a 
triangular  membranous  prolongation,  lining  the  poste- 
rior part  of  the  corpus  callosum,  and  the  inferior  surface 
of  the  fornix,  to  which  it  adheres  by  numerous  small 
vessels.  2d,  the  choroid  plexus,  an  elongated  fold  of 
the  pia  mater,  having  an  appearance  of  vascular  cords, 
attached  to  the  choroid  web,  and  extending  into  the  lat- 
eral ventricles,  along  the  sides  of  the  fornix  ; this  plexus 
communicates  with  that  part  of  the  external  pia  mater 
which  descends  between  the  thalami  of  the  optic  nerves 
and  the  fimbriated  bodies.  We  perceive  in  the  choroid 
plexus  a number  of  small  granulations  which  many  ana- 
tomists have  considered  as  glands  ; but  Chaussier  asserts 
that  they  are  membranous  fringes,  which  may  be  unfolded 
by  agitating  them  in  water.  We  also  occasionally  find 
among  the  vessels  of  this  plexus  small  vesicles  filled  with 
serum. 


GRANULATIONS  OF  THE  MEMBRANES  OF  THE  BRAIN. 

On  the  various  parts  of  the  dura  and  pia  mater,  there 
are  small  whitish  bodies,  of  the  intimate  texture  and  office 
of  which  we  are  entirely  ignorant. 

The  superior  longitudinal  sinus  contains  a great  number 
of  these  granulations  ; they  are  designated  by  the  name  of 
the  glands  of  Pacchioni. 

Sometimes  a few  of  them  are  found  in  the  torcular 
HEROPHiLi,  and  at  the  orifices  of  the  vena3  galeni.  All 
the  other  sinuses  are  destitute  of  them. 

Graniform  bodies,  similar  to  those  met  with  in  the 
sinuses,  are  also  found  in  the  pia  mater,  especially  about 


NERVOUS  SYSTEM. 


81 


the  outside  of  the  superior  longitudinal  sinus,  and  around 
the  cerebral  veins. 

The  internal  pia  mater  contains  some  of  these  granu- 
lations ; they  are  also  observed  in  the  choroid  plexus, 
the  velum  interpositum,  and  in  the  web  of  the  fourth  ven- 
tricle. 


THE  PROPER  MEMBRANE  OF  THE  SPINAL  MARROW. 

The  character  of  this  membrane  is  sufficiently  marked 
to  distinguish  it  from  the  pia  mater.  It  is  not,  therefore, 
a continuation  of  the  latter,  but  a strong  and  somewhat 
fibrous  tissue,  of  a yellowish  color,  corresponding,  by  its 
external  surface,  to  the  arachnoid,  without  uniting  with  it ; 
laterally  it  is  continuous  with  the  neurilemma  of  the  verte- 
bral nerves,  and  ligamentum  denticulatum.  By  its  internal 
surface  it  is  adherent  to  the  spinal  marrow. 


LIGAMENTUM  DENTICULATUM. 

The  ligamentum  denticulatum  is  a whitish,  transparent, 
thin,  but  strong  band,  extending,  on  each  side,  between 
the  anterior  and  posterior  roots  of  the  vertebral  nerves, 
from  the  occipital  foramen,  to  the  termination  of  the  spinal 
marrow.  In  the  interval  of  each  cervical  and  dorsal  pair 
of  nerves,  its  external  border  presents  twenty  or  twenty- 
two  denticulated  portions,  the  points  of  which  are  fixed  to 
the  dura  mater.  Its  internal  border  adheres  to  the  proper 
membrane  of  the  spinal  marrow.  Its  use  appears  to  be  to 
keep  the  spinal  marrow  steady  in  its  canal. 

11 


VOL.  II. 


82 


NERVOUS  SYSTEM. 


THE  NERVES  IN  GENERAL. 

The  nerves  are  either  cylindrical  or  flattened  white  cords, 
which  are  extended  from  the  brain,  or  from  the  spinal  mar- 
row, to  every  part  of  the  system. 

All  the  nerves  are  arranged  symmetrically  and  in  pairs, 
and  are  composed  of  a greater  or  less  number  of  filaments, 
connected  together  by  cellular  tissue.  The  filaments  which 
terminate  the  branches  of  the  nerves  unite  with  other 
nervous  filaments,  or  elude  our  observation  in  the  tissue 
of  the  organs  which  they  supply.  Fig.  22,  a portion  of  a 


Fig.  22. 


nerve  invested  with  its  neurilemma,  and  consisting  of  dis- 
tinct filaments,  one  of  which  is  drawn  out. 

If  two  or  more  nervous  branches  are  connected  together 
by  numerous  filaments  sent  to  each  other,  so  that  there 
results  a sort  of  net-work,  the  name  of  plexus  is  given  to 
this  distribution.  Fig.  23,  is  an  instance  drawn  from  the 
axillary  plexus. 


Fig.  23. 


NERVOUS  SYSTEM. 


83 


Most  of  the  nerves  are  composed  of  a greater  or  less 
number  of  cords,  formed  of  filaments  of  the  same  nature. 
On  separating  these  cords  and  fibres,  we  perceive  that  they 
send  frequent  branches  to  each  other,  so  as  to  form  a kind 
of  plexus  in  the  very  substance  of  the  nerve. 

The  neurilemma  is  the  external  membrane  which  forms  a 
canal  for  the  white  medullary  matter  of  the  nerve  : this 
may  be  readily  shewn  by  immersing  a nerve  in  an  alkaline 
solution,  by  which  the  medullary  matter  is  removed  ; and 
the  nerve  appears  like  a fasciculus  of  tubes.  The  olfactory 
nerve  has  no  neurilemma,  and  it  is  only  found  round  the 
optic  nerve  after  its  commissure. 

The  nerves  are  amply  supplied  with  blood  vessels,  which 
are  distributed  on  their  surface,  and  penetrated  into  their 
substance,  and  between  their  component  fasciculi. 

In  some  of  the  principal  nerves  absorbent  vessels  may 
be  traced,  and  reasoning  from  analogy,  we  may  conclude 
that  there  are  no  nerves  destitute  of  them. 

NERVES  OF  THE  CEREBRAL  DEPARTMENT. 

By  the  older  anatomists,  the  cerebral  nerves  were  divi- 
ded into  nine  pairs ; the  facial  and  auditory  nerves  being 
termed  the  seventh  pair,  and  the  eighth  consisting  of  the 
glosso-pharyngaeal,  par  vagum  and  the  spinal  accessory. 
The  division  at  present  adopted,  is  into  twelve  pairs. 


OLFACTORY  NERVES,  OR  FIRST  PAIR. 

The  olfactory  nerves  are  very  soft  in  their  texture,  and 
after  death  are  soon  decomposed  ; they  should,  therefore, 
be  demonstrated  in  a recent  subject.  They  are  connected 
to  the  brain  by  three  filaments;  the  1st,  is  external  and 


84 


NERVOUS  SYSTEM. 


medullary,  and  is  in  union  with  the  corpus  striatum  ; the 
2d,  internal  and  medullary,  is  united  to  the  white  sub- 
stance which  occupies  the  internal  part  of  the  fissure  of 
SYLVIUS  ; the  3d  is  cortical,  and  is  situated  at  the  point  of 
junction  of  the  two  preceding,  uniting  to  them  by  its 
summit.  At  the  point  of  their  union,  the  olfactory  nerve 
presents  a triangular  enlargement.  Fig.  24,  a,  extending 


Fig.  24. 


horizontally  forwards  and  inwards,  and  dividing  into  a 
greater  or  less  number  of  branches  which  traverse  the  fora- 
mina of  the  cribriform  plate  of  the  ethmoid  bone,  to  be 
distributed  at  d,  on  the  turbinated  bones  of  the  nasal  fossa, 
the  septum  narium,  and  the  roof  of  the  nasal  fossa. 

This  nerve  transmits  to  the  brain  the  impression  which 
odours  produce  upon  the  pituitary  membrane. 


OPTIC  NEKVES,  OR  SECOND  PAIR. 

The  optic  nerve,  with  the  exception  of  the  trifacial  nerve, 
is  the  largest  nerve  that  issues  from  the  cranium.  It 
is  connected  to  the  optic  thalami  and  the  tubercula  qua- 
drigemina  by  two  bands,  which  are  extended  from  these 
eminences  to  the  optic  thalami.  The  two  nerves  unite 


NERVOUS  SYSTEM. 


85 


in  front  of  the  pituitary  fossa,  and  are  so  confounded  with 
each  other,  as  to  render  it  impossible  to  affirm,  in  a posi- 
tive manner,  whether  they  cross  each  other,  as  many  ana- 
tomists have  supposed,  or  whether  their  substance  is 
mingled  and  identified  at  their  union ; the  latter  opinion  is 
most  probable. 

The  optic  nerves  afterwards  separate  ; each  nerve  being 
perfectly  cylindrical,  isolated  and  enveloped  in  a neuri- 
lemma ; it  then  passes  through  the  optic  foramen,  and  sur- 
rounded by  the  recti  muscles  in  the  orbit,  arrives  at  the 
posterior  and  inner  part  of  the  globe  of  the  eye ; entering 
the  sclerotic  and  choroid  membranes,  it  terminates  in  the 
retina. 


The  third  pair,  or  motores  oculoruin,  Fig.  25,  a,  are 
smaller  than,  c,  the  optic  nerve  ; each  nerve  is  attached  to 
the  back  part  of  the  crura  cerebri,  by  filaments  which  are 


soon  collected  into  their  several  trunks.  These  pass  on 
the  upper  part  of  the  cavernous  sinus,  on  the  outside  of 
the  foramen  lacerum,  into  the  orbit,  and  divide  into  the 
following  branches  : 1st,  the  superior  branch,  e,  e,  which  is 


THIRD  PAIR  OF  NERVES, 


Fig.  35. 


86 


NERVOUS  SYSTEM. 


distributed  to  the  superior  rectus  and  levator  palpebrae  ; 
2d,  the  inferior  branch,/,  which  supplies  the  other  recti 
muscles ; 3d,  a filament  to  the  lenticular  ganglion,  and  in- 
ferior oblique  muscle. 

FOURTH  PAIR  OF  NERVES. 

The  fourth  pair  of  nerves  or  nei'vi  pathetici,  b,  are  the 
most  slender  of  the  body.  Each  nerve  is  attached  by  three 
or  four  filaments,  beneath  the  tubercula  quadrigemina,  and 
the  lateral  part  of  the  valve  of  Vieussens.  This  nerve 
turns  round  the  crus  cerebri,  perforates  the  dura  mater  at 
the  edge  of  the  tentorium,  passes  the  cavernous  sinus  on 
the  outer  side  of  the  third  nerve,  and  proceeds  through  the 
foramen  lacerum,  to  supply  the  superior  oblique  muscle  of 
the  eye. 


FIFTH  PAIR,  OF  TRIFACIAL  NERVES. 

The  trifacial  nerves  are  the  largest  of  the  brain  ; they 
are  attached,  first,  between  the  corpora  olivaria  and  resti- 
formia  by  a fasciculus  of  white  fibres,  which  ascend  above 
the  posterior  part  of  the  pons  varolii,  at  the  outer  edge 
of  which  they  leave  the  brain  ; each  forms  a large  flat  cord, 
composed  of  two  distinct  fasciculi ; the  one  anterior,  con- 
sisting of  five  or  six  filaments  ; the  other,  which  is  posteri- 
or, forms  a grayish  enlargement,  termed  the  Gasserian 
ganglion,  from  the  anterior  part  of  which  proceed  three 
branches ; viz.  the  ophthalmic,  the  superior  maxillary,  and 
the  inferior  maxillary. 


NERVOUS  SYSTEM. 


87 


1.  THE  OPHTHALMIC,  OR  FIRST  BRANCH  OF  THE  FIFTH  PAIR  OF 

NERVES. 

The  ophthalmic  nerve  passes  the  external  part  of  the 
cavernous  sinus,  receiving  a filament  from  the  superior 
cervical  ganglion,  and,  passing  through  the  foramen  lace- 
rum  orbitale,  divides  into  the  lachrymal,  the  frontal,  and 
the  nasal  nerves. 

The  lachrymal  nerve  proceeds  along  the  external  part  of 
the  orbit,  gives  off  the  spheno-maxillary  branch,  which 
unites  with  a branch  of  the  superior  maxillary  nerve  ; and 
the  molar  branch,  which  unites  with  a branch  of  the  facial 
nerve  ; it  furnishes  also  several  branches  to  the  lachrymal 
gland,  and  to  the  superior  eyelid. 

HhQ  frontal  nerve  is  found  in  the  upper  part  of  the  orbit, 
where  it  divides  into  two  filaments.  The  internal  frontal, 
which  is  distributed  to  the  frontal  sinus,  the  corrugator 
supercilii,  and  frontalis  muscles,  and  the  subcutaneous  cel- 
lular tissue  of  the  forehead. 

The  external  frontal  filament,  passes  through  the  supra 
orbitary  foramen,  and  is  distributed  to  the  frontalis  mus- 
cles, and  to  the  integuments  extending  over  the  summit  of 
the  head. 

The  nasal  nerve  passes  under  the  superior  oblique  mus- 
cle ; it  frequently  receives  a filament  from  the  superior 
cervical  ganglion,  and  furnishes  a very  delicate  filament  to 
the  lenticular  ganglion,  and  also,  two  or  three  ciliary  fila- 
ments : it  at  length  divides  into  two  branches  ; the  internal 
nasal,  which  re-enters  the  cranium  by  the  anterior  in- 
ternal orbitary  foramen,  and  from  thence  again  passes 
down  through  one  of  the  perforations  of  the  cribriform 
plate  of  the  ethmoid  bone,  to  be  distributed  to  the  septum 
narium  and  the  nasal  fossae.  The  external  branch  passes 
out  of  the  orbit,  beneath  the  pulley  of  the  superior  oblique 


88 


NERVOUS  SYSTEM. 


muscle,  and  is  distributed  to  the  lachrymal  passages  and 
dorsum  of  the  nose. 

2.  THE  SUPERIOR  MAXILLARY  NERVE,  OR  SECOND  BRANCH  OF  THE 

FIFTH  PAIR. 

The  superior  maxillary  nerve  is  extended  from  the  gang- 
lion of  the  fifth  pair  ; it  enters  through  the  foramen  ro- 
tundum  of  the  sphenoid  bone  into  the  spheno-maxillary 
fossa,  where  it  receives  filaments  from  the  spheno-palatine 
ganglion  ; it  then  passes  through  the  infra-orbitar  canal 
and  terminates  on  the  cheek.  It  furnishes,  1st,  the  or- 
bital branch  which  passes  into  the  orbit  by  the  spheno- 
maxillary fissure,  and  there  divides  into  the  malar  and 
temporal  filaments.  2d.  The  posterior  and  superior  den- 
tal branches  which  enter  the  passages  in  the  maxillary 
tuberosity,  and  dividing  into  many  filaments  are  distri- 
buted to  the  roots  of  the  three  last  molar  teeth,  and  to 
the  gums.  3d.  The  anterior  dental  branch  which  de- 
scends into  the  anterior  dental  canal,  and  divides  into 
filaments,  which  are  distributed  to  the  incisor,  the  canine, 
and  the  two  small  molar  teeth.  4th.  The  infra-orbitar 
branches  which  form  the  termination  of  the  superior  max- 
illary nerve  ; these  pass  out  by  the  infra-orbitar  foramen, 
and  uniting  with  filaments  from  the  facial,  nasal  and  buccal 
branches,  are  distributed  to  the  muscles  and  integuments 
of  the  cheek. 

3.  THE  INFERIOR  MAXILLARY  NERVE,  OR  THIRD  BRANCH  OF  THE 

FIFTH  PAIR. 

The  inferior  maxillary  nerve  passes  through  the  fora- 
men ovale  of  the  sphenoid  bone,  and  is  distributed  to 
the  lower  jaw,  and  the  muscles  situated  between  it 


NERVOUS  SYSTEM. 


89 


and  the  os  hyoides ; it  furnishes  the  following  branches 
viz,  — 

1st.  Two  deep  temporal  nerves  which  are  distributed  to 
the  inner  part  of  the  temporal  muscle. 

2d.  The  masseteric  nerves  which  are  distributed  to  the 
articulation  of  the  jaw  and  the  masseter  muscle, 

3d,  The  buccal  nerve  which  passes  between  the  ptery- 
goid muscles,  and  divides  into  six  or  seven  filaments  which 
are  distributed  to  the  temporal,  buccinator,  and  levator 
anguli  oris  muscles,  to  the  angle  of  the  mouth,  and  finally 
to  the  integuments. 

4th.  The  pterygoid  nerves,  two  very  delicate  filaments 
which  are  directed  downwards,  and  terminate  in  the  inter- 
nal pterygoid  muscles. 

5th.  The  lingual  or  gustatory  nerve,  of  considerable  size, 
and  which  receives  the  filament  called  the  corda  tympani, 
which  extends  from  the  spheno-palatine  ganglion.  The 
lingual  nerve  afterwards  descends  between  the  pterygoidei 
muscles,  and  furnishes  in  its  passage  a filament  to  the  in- 
ternal pterygoid  muscle  ; several  to  the  tonsils  and  to  the 
superior  constrictor  of  the  pharynx  ; two  or  three  to  the 
back  part  of  the  gums,  and  to  the  submaxillary  gland  ; 
several  filaments  are  distributed  to  the  sublingual  gland, 
and  to  the  mucous  membrane  of  the  mouth  : lastly,  it 
divides  into  numerous  filaments  which  penetrate  the  mus- 
cular tissue  of  the  tongue,  and  ascending  towards  the  supe- 
rior surface  terminate  in  the  numerous  papillae  ; in  conse- 
quence of  which,  this  branch  is  considered  as  the  principal 
nerve  of  the  organ  of  taste. 

6th.  The  inferior  dental  nerve,  which  enters  the  dental 
canal,  and  is  divided  into  branches  which  are  distributed 
to  the  teeth  and  to  the  cancelli  of  the  bone  : some  fila- 
ments, named  the  mental  nerves,  pass  out  of  the  anterior 
maxillary  foramen,  and  are  distributed  to  the  lower  lip  and 
chin. 


VOL.  II. 


12 


90 


NERVOUS  SYSTEM. 


The  auricular  or  superficial  temporal  nerve,  proceeds 
backwards  and  outwards  between  the  condyle  of  the  jaw 
and  the  auditory  canal ; it  communicates  with  the  facial 
nerve,  giving  off  branches  to  the  temporo-maxillary  arti- 
culation, and  to  the  pavilion  and  integuments  of  the  ear  ; 
it  is  ultimately  distributed  to  the  integuments  of  the  tem- 
ples and  forehead. 


Fig.  26. 


Fig.  26,  exhibits  the  trifacial  nerve  and  the  distribution 
of  its  three  principal  branches. 
a,  the  trunk  of  the  trifacial  nerve. 
q,  the  Gasserian  ganglion. 
h,  the  frontal. 

/,  the  lachrymal. 

g,  the  nasal  nerves  of  the  ophthalmic  branch. 


NERVOUS  SYSTEM. 


91 


r,  the  superior  maxillary  branch. 
I,  the  malar. 

i,  the  anterior  dental. 
h,  the  posterior  dental. 

Tc,  the  infra  orbitar  nerves, 
c,  the  inferior  maxillary  branch 

s,  the  two  deep  temporal. 

t,  the  masseteric. 

0,  the  lingual. 

e,  the  inferior  dental. 
p,  the  sublingual  nerves. 


SIXTH  PAIR  OF  NERVES. 

The  sixth  pair  of  nerves  are  very  small ; they  are  at- 
tached to  the  sides  of  the  corpora  pyramidalia,  each  pro- 
ceeds to  the  line  which  separates  the  pons  varolii  from 
the  medulla  oblongata ; here  the  filaments  unite  and  pro- 
ceed along  the  basilar  groove  through  the  cavernous  sinus, 
pass  through  the  foramen  lacerum  orbitale,  and  are  distri- 
buted to  the  external  rectus  muscle  of  the  eye. 

While  in  the  cavernous  sinus,  the  sixth  nerve  is  placed 
between  the  ophthalmic  nerve  and  the  carotid  artery,  upon 
the  surface  of  the  latter  of  which,  two  or  three  filaments 
are  extended  to  the  great  sympathetic  nerve. 


SEVENTH  PAIR  OF  NERVES,  OR  FACIAL  NERVES. 

The  facial  nerve  is  the  portio  dura  of  the  old  anato- 
mists ; it  appears  beneath  the  posterior  and  external  part 
of  the  pons  varolii,  from  the  line  between  the  corpora 
olivaria  and  restiformia ; it  enters  the  internal  auditory 
foramen  with  the  acoustic  nerve,  then  leaves  the  latter  to 


92 


NERVOUS  SYSTEM. 


proceed  into  the  aqueduct  of  fallopius,  passing  out  of 
the  cranium  by  the  stylo-mastoid  foramen.  On  a level 
with  the  hiatus  fallopii,  it  receives  a filament  of  the 
Vidian  nerve,  which  enters  the  cavity  of  the  tympanum, 
under  the  name  of  corda  tympani.  The  facial  nerve  also 
furnishes  filaments  to  the  muscles  of  the  tympanum,  the 
pavilion,  and  the  integuments  of  the  ear.  On  its  exit 
from  the  stylo-mastoid  foramen,  it  gives  off  the  pos- 
terior auricular,  the  stylo-hyoid,  and  the  sub-mastoid 
branches. 

The  facial  nerve  then  enters  the  parotid  gland,  and  is 
distributed  to  the  muscles  and  the  integuments  of  the  face. 
These  branches  separate  and  reunite  at  different  places,  so 
as  to  form  a plexus  on  the  side  of  the  face,  which  has  been 
called  the  pes  anserinus. 


NERVOUS  SYSTEM. 


93 


Fig.  27. 


Fig.  27,  exhibits  the  superficial  nerves  of  the  face  and 
neck : the  parotid  gland  is  removed  to  shew  the  divisions 
of  the  facial  nerve  which  pass  through  it. 

a,  the  divisions  of  the  facial  nerve,  termed  the  pes  anse- 
rinus. 

h,  the  supra  orbitary  nerve. 

c,  the  infra  orbitary  nerve. 

d,  the  mental  nerves. 

e,  the  first  cervical  nerve. 

/,  descending  branches  communicating  with  the  hypo- 
glossal and  cervical  nerves. 


94 


NERVOUS  SYSTEM. 


EIGHTH  PAIR,  OR  AUDITORY  NERVES. 

The  auditory  nerve  is  the  portio  mollis  of  the  old  anato- 
mists. It  is  attached  over  the  restiform  body,  from  the 
substance  of  a small  gray  band,  which  unites  it  to  the 
floor  of  the  fourth  ventricle.  We  may  observe  also  a 
small  band  which  seems  to  unite  this  part  of  the  auditory 
nerve,  and  furnishes  it  with  a commissure.  This  nerve  ac- 
companies the  facial,  so  long  as  it  is  contained  in  the  skull 
and  internal  auditory  canal ; but  at  the  bottom  of  this 
canal  it  divides  into  branches,  which  are  distributed  to  the 
cochlea,  the  vestibule  and  the  semicircular  canals.  In  the 
description  of  the  organ  of  hearing,  these  will  be  particu- 
larly noticed.  This  nerve  transmits  to  the  brain  the  im- 
pressions which  sound  produces  upon  the  internal  ear. 


NINTH  PAIR  OF  NERVES. 

The  glosso-pharyngeal,  or  ninth  pair  of  nerves,  is  at- 
tached in  the  line  which  separates  the  corpora  olivaria  from 
the  corpora  restiformia  ; each  nerve  has  three  or  four  fila- 
ments which  unite  into  a single  cord,  which  is  directed 
through  the  foramen  lacerum,  and  is  separated  from  the 
pneumo-gastric  nerve  by  the  internal  jugular  vein.  After 
its  exit  from  the  cranium,  it  sends  a filament  to  the  audi- 
tory canal,  receives  a filament  from  the  facial,  and  another 
from  the  pneumo-gastric  nerve  ; several  filaments  are  dis- 
tributed to  the  carotid  artery,  and  others  communicate  with 
the  cervical  ganglia.  It  gives  branches  also  to  the  muscles 
of  the  pharynx,  to  the  mucous  glands,  to  the  fauces,  and  at 
length  terminates  in  the  tongue. 

It  gives  motion  to  the  muscles  of  the  tongue  and  pha- 
rynx, but  more  especially  to  those  necessary  for  the  articu- 
lation of  the  voice. 


NERVOUS  SYSTEM. 


95 


TENTH  PAIR  OF  NERVES. 

The  pneumo-gastric  nerves,  or  par  vagum,  sometimes 
called  the  eighth  pair,  are  connected  to  the  brain,  immedi- 
ately beneath  the  preceding,  behind  the  corpora  olivaria, 
near  the  corpora  restiformia.  Each  commences  by  numer- 
ous filaments,  which  unite  and  form  two  or  three  fasciculi, 
placed  under  each  other ; but,  on  passing  out  of  the  cra- 
nium through  the  foramen  lacerum  posterius,  they  form  a 
round  cord,  which  descends  with  the  great  sympathetic,  on 
the  lateral  part  of  the  neck,  on  the  outer  side  of  the  primi- 
tive carotid,  and  posterior  to  the  jugular  vein ; it  passes 
into  the  chest  behind  the  subclavian  vein,  and  accompanies 
the  oesophagus  to  the  stomach.  It  presents  a multitude  of 
variations  in  its  secondary  divisions,  so  that  we  seldom  find 
it  alike  in  two  subjects  ; but  it  constantly  furnishes  — 

1st.  The  pharyngeal  nerve,  which  is  distributed  to  the 
pharynx,  and  forms  the  pharyngeal  plexus. 

2d.  The  superior  laryngeal  nerve,  which  is  distributed 
to  the  muscles  of  the  larynx,  the  thyroid  gland,  and  the 
mucous  membrane  of  the  larynx  and  pharynx. 

3d.  The  cardiac  nerves.  On  the  right  side  the  pneu- 
mo-gastric nerve  supplies  two  or  three  filaments,  descending 
with  itself  to  the  stomach,  and  uniting  with  the  cardiac 
filaments  of  the  cervical  ganglion ; on  the  left  side  it  fur- 
nishes only  one  filament,  which  terminates  in  the  cardiac 
plexus.  r- 

4th.  The  recurrent  or  inferior  laryngeal  nerves.  These 
differ  on  the  right  and  left  sides ; the  left  turns  round  the 
arch  of  the  aorta ; the  right  passes  round  the  subclavian 
artery  ; both  ascend  on  the  side  of  the  trachea,  and  termi- 
nate at  the  larynx. 


96 


NERVOUS  SYSTEM, 


Fig.  28. 


Fig.  28,  exhibits  the  general  course  of  the  deep  seated 
nerves  of  the  neck  and  thorax. 

a,  the  superior  cervical  ganglion  of  the  gi’eat  sympathe- 
tic nerve. 

b,  the  middle  cervical  ganglion. 


NERVOUS  SYSTEM. 


97 


c,  the  pneumo-gastric  nerve. 

d,  d,  the  recurrent,  or  inferior  laryngeal  nerve. 

I,  the  pharyngeal  nerve. 

■ t,  the  superior  laryngeal  nerve. 

s,  the  cardiac  plexus. 

n,  the  coronary  nerves. 

Tc,  k,  k,  the  cervical  nerves,  forming  the  brachial  plexus. 

o, p,  the  cervical  plexus. 

i,  the  commencement  of  the  phrenic  nerve  from  the 
fourth  cervical  nerve,  g,  its  course  over  the  lungs  to  the 
diaphragm. 

The  pneumo-gastric  nerve  gives  filaments  to  the  oeso- 
phagus and  stomach  ; it  also  unites  by  numerous  radiations 
with  the  hepatic,  the  splenic,  the  coeliac,  and  the  right  gas- 
tro-epiploic  plexus  : other  filaments  are  interlaced  with  the 
meshes  of  the  solar  plexus,  and  several  expand  on  the  vena 
portae,  the  pancreas,  the  duodenum,  and  the  gall  bladder. 

On  account  of  the  very  extensive  distribution,  and  nu- 
merous communications  of  the  pneumo-gastric  nerve,  it  is 
called  by  some  authors  the  middle  sympathetic  nerve. 


ELEVENTH  PAIR,  OR  HYPOGLOSSAL  NERVES. 

The  hypoglossal  nerve  is  connected  by  several  filaments 
with  the  fissure  which  separates  the  olivary  and  pyramidal 
eminences ; these  filaments  form  a cord,  which  passes  out 
of  the  cranium  by  the  anterior  condyloid  foramen.  The 
hypoglossal  is  then  united  to  the  pneumo-gastric  nerve  for 
a short  distance,  but  at  the  angle  of  the  jaw  it  is  directed 
downwards  and  forwards,  curving  under  the  tendon  of  the 
digastricus,  towards  the  tongue.  From  the  convexity  of 
the  curve  it  gives  off,  — 

The  descending  cervical  branch.  In  the  former  mode  of 
enumerating  the  cranial  nerves,  it  was  termed  the  descend- 
13 


VOL.  II. 


98 


NERVOUS  SYSTEM. 


cns  noni;  it  passes  in  front  of  the  internal  jugular  vein,  and 
communicates  with  the  internal  branch  of  the  cervical  plex- 
us. The  hypoglossal  nerve  then  passes  between  the  mylo- 
hyoideus  and  hyoglossus  ; it  furnishes  branches  to  the 
adjacent  muscles,  and  is  finally  distributed  to  the  tongue. 

It  gives  the  power  of  motion  to  the  muscles  of  the 
tongue  ; principally,  however,  to  those  concerned  in  the 
process  of  mastication  and  deglutition. 


TWELFTH  PAIR,  OR  ACCESSORY  NERVE  OF  WILLIS. 

The  spinal  accessory  nerve  (called  by  Sir  Charles  Bell 
the  superior  respiratory  of  the  trunk)  is  singular  in  its  ori- 
gin and  progress.  It  commences  at  the  lateral  parts  of  the 
spinal  cord  ; the  first  point  of  union  with  the  medulla 
spinalis  is  about  the  sixth  vertebra  of  the  cervical  region  ; 
it  ascends  between  the  ligamentum  denticulatum  and  pos- 
terior roots  of  the  cervical  nerves,  receiving  from  the  latter 
new  filaments  which  increase  its  size  ; it  then  passes  through 
the  great  occipital  foramen,  and  makes  its  exit  by  the  for- 
amen lacerum  posterius  with  the  pneumo-gastric,  to  which 
it  sends  a filament ; it  then  leaves  the  latter  and  adheres  to 
the  hypoglossal,  from  which  it  again  separates,  passes 
through  the  sterno-cleido-mastoideus  muscle,  and  termi- 
nates in  the  trapezius.  Fig.  28,  m. 

Recent  investigations  have  decidedly  proved,  that  the 
spinal  accessory  nerve,  both  in  its  commencement  and  dis- 
position, conforms  to  the  spinal  nerves,  and  is  never 
deprived  of  a posterior  root,  as  some  have  imagined. 

This  nerve  gives  the  power  of  motion  to  the  sterno- 
cleido-mastoideus,  and  to  the  trapezius. 


NERVOUS  SYSTEM. 


99 


Fig.  29. 


This  figure  was  before  given  to  shew  the  basis  of  the 
brain,  etc.  It  is  again  introduced  to  e.xhibit  the  com- 
mencement of  the  cerebral  nerves.  They  are  numbered, 
as  they  have  been  described,  according  to  the  most  modern 
arrangement. 

1,  the  olfactory  nerve,  having  several  roots  behind,  and 
a bulbous  extremity  before. 

2,  2,  the  optic  nerves  united  before,  ??,  the  infundibulum. 

3,  the  common  motor  nerve. 

4,  the  patheticus. 

5,  the  trigeminus. 

6,  the  abducens  or  external  motor  nerve. 


100 


NERVOUS  SYSTEM. 


7,  the  facial  nerve,  or  portio  dura, 

8,  the  auditory  nerve,  or  portio  mollis. 

9,  the  glosso-pharyngeal  nerve. 

10,  the  pneumo-gastric  nerve, 

11,  the  hypoglossal  nerve. 

12,  the  spinal  accessory. 


SPINAL  NERVES.  ' 

The  spinal  nerves  are  divided  into  four  orders,  viz.  the 
cervical,  the  dorsal,  the  lumbar,  and  the  sacral. 

The  nerves  of  the  spinal  cord,  which  have  been  pre- 
viously enumerated,  commence  by  two  species  of  roots. 
Each  of  these  roots  is  formed  by  a number  of  distinct  fila- 
ments, but  in  their  passage  through  the  intervertebral  fora- 
mina they  unite  ; the  posterior  root,  at  their  union,  forms 
a ganglion.  See  Fig.  12. 

The  1st  order  of  spinal  nerves  are  the  cervical,  nine 
pairs. 

The  2d  order,  the  dorsal  nerves,  twelve  pairs. 

The  3d  order,  the  lumbar  nerves,  five  pairs. 

The  4th  order,  the  sacral  nerves,  six  pairs. 


FIRST  PAIR  OF  CERVICAL  NERVES. 

'Yhe  first  pair  of  cervical  nerves  commences  at  the  sides 
of  the  spinal  cord,  beneath  its  superior  enlargement ; each 
nerve  proceeds  from  the  vertebral  canal,  between  the  atlas 
and  dentata,  and  divides  into  two  parts  : the  first  of  which 
is  joined  to  the  accessory  nerve,  and  by  branches  of  the 
hypoglossal ; it  is  also  connected  by  a gangliform  root, 
with  the  upper  ganglion  of  the  sympathetic  nerve,  and  it 
crives  filaments  to  muscles  connected  with  the  anterior  part 


NERVOUS  SYSTEM. 


101 


of  the  cervical  vertebrae.  The  second  part  of  this  nerve  is 
distributed  to  the  extensors  of  the  head  and  neck,  and 
forms  the  occipital  nerve. 


SECOND  PAIR  OF  CERVICAL  NERVES. 

The  anterior  branch  of  this  pair  of  cervical  nerves  passes 
between  the  transverse  processes  of  the  two  first  vertebrae, 
and  divides  into  numerous  filaments,  one  of  which  unites 
with  the  first  pair;  another  joins  the  superior  cervical 
ganglion  ; a third  is  distributed  to  the  anterior  rectus  of 
the  head  ; a fourth  contributes  to  form  a cervical  plexus ; 
and  a fifth  communicate  with  the  pneumo-gastric  nerves. 

The  posterior  branch  is  reflected  upwards,  under  the 
obliquus  capitis  inferior,  traverses  the  great  complexus,  and 
is  distributed  to  the  occipito-frontalis  muscle  and  to  the  in- 
teguments. 

THIRD  AND  FOURTH  PAIRS  OF  CERVICAL  NERVES. 

The  third  and  fourth  cervical  nerves  proceed  in  similar 
directions  ; the  anterior  part  sending  off  branches  to  form 
the  cervical  plexus  ; while  the  posterior  supplies  the  mus- 
cles and  integuments  of  the  back  part  of  the  neck. 

CERVICAL  PLEXUS. 

The  cervical  plexus  is  situated  on  the  lateral  part  of  the 
neck,  on  a level  with  the  second,  third,  and  fourth  verte- 
brae, and  is  formed  by  the  anterior  branches  of  the  second, 
third  and  fourth  cervical  nerves,  which  communicate  and 
form  arches,  the  convexities  of  which  send  off  filaments. 


102 


NERVOUS  SYSTEM. 


which  again  unite,  and  communicate  superiorly  with  the 
first  pair  ; inferiorly,  with  the  brachial  plexus.  The  cervical 
furnishes  very  many  ascending  and  descending  branches. 

1st.  The  internal  descending  branch,  formed  by  two  fila- 
ments of  the  second  and  third  pair,  which  uniting  descends 
on  the  sterno-cleido-mastoideus  muscle,  and  communicates 
with  the  hypoglossal  nerve. 

2d.  Thep/tremc  nerve  or  the  internal  respiratory  nerve, 
is  principally  composed  of  a branch  of  the  fifth  pair,  but 
receives  a filament  from  the  fourth,  and  two  or  three  from 
the  brachial  plexus  ; it  descends  upon  the  anterior  part  of 
the  neck,  between  the  anterior  rectus  and  anterior  scalenus 
muscles,  communicating  with  the  inferior  cervical  ganglion, 
and  passing  into  the  thorax  between  the  subclavian  artery 
and  subclavian  vein  ; it  enters  the  anterior  mediastinum, 
then  descends  between  the  pleura  and  the  lateral  parts  of 
the  pericardium,  and  terminates  in  numerous  filaments 
which  ramify  on  the  superior  surface  of  the  diaphragm. 
See  Fig.  28,  i,  g. 

3d.  The  external  descending  branches  of  the  cervical 
plexus,  are  distributed  in  numerous  filaments  to  the  mus- 
cles and  integuments  of  the  mastoid,  auricular,  and  scapu- 
lar regions.  Some  are  superficial,  others  deep.  The 
superficial  descend  to  the  clavicle  and  acromion  process, 
supply  the  superficial  muscles  in  their  course,  and  terminate 
in  the  pectoral  and  deltoid  muscles,  and  in  the  integuments. 
The  deep  branches  descend  behind  the  clavicle,  supply  the 
deep  muscles  on  the  side  of  the  neck,  and  those  connected 
to  the  scapula.  One  of  these  branches,  remarkable  for  its 
length,  and  of  the  same  size  of  the  phrenic,  is  named  the 
external  respiratory  nerve.  This  nerve  proceeds  from  the 
back  part  of  the  plexus,  chiefly  from  the  fourth  cervical. 
It  has  also  filaments  connecting  it  to  the  third  and  second 
and  to  the  phrenic.  It  descends  behind  the  scaleni  mus- 
cles and  beneath  the  trapezius  and  levator  anguli  scapulae. 


NERVOUS  SYSTEM. 


103 


and  is  almost  exclusively  distributed  to  the  serratus  magnus 
muscle. 

4th.  The  superficial  ascending  branches  are  derived  prin- 
cipally from  the  third  pair ; they  are  distributed  to  the 
sterno-cleido-mastoideus,  the  platysma  myoides,  the  skin 
of  the  neck,  and  the  inferior  maxillary  region,  and  com- 
municate with  the  facial  nerve. 

FOURTH,  FIFTH,  SIXTH,  AND  SEVENTH  PAIRS  OF  CERVICAL 

NERVES. 

The  posterior  branches  of  these  nerves  descend  obliquely 
outwards,  traverse  the  splenius  and  trapezius,  and  are  dis- 
tributed to  the  muscles  and  integuments  of  the  back  part 
of  the  neck. 

The  anterior  branches  furnish  filaments  which  communi- 
cate with  the  cervical  ganglia,  and  some  others  which  are 
distributed  to  the  scaleni  muscles  : they  then  communicate 
and  form  the  brachial  plexus.  It  may  be  observed,  that  a 
filament  of  the  fourth  contributes  to  the  formation  of  the 
phrenic  nerve. 

BRACHIAL  OR  AXILLARY  PLEXUS. 

The  brachial  plexus  consists  of  an  interlacement  of  the 
anterior  branches  of  the  last  four  cervical  nerves  and  the 
first  dorsal.  The  brachial  plexus  extends  from  the  lateral 
and  inferior  part  of  the  neck  to  the  axilla,  where  it  divides 
into  several  branches,  which  are  distributed  to  the  thorax, 
shoulder  and  arm.  ^ It  is  situated  between  the  scaleni  mus- 
cles, and  above  the  subclavian  artery. 


104 


NERVOUS  SYSTEM. 


THORACIC  BRANCHES. 

The  anterior  thoracic  branch  is  chiefly  derived  from  the 
seventh  cervical  nerve  ; it  descends  behind  the  clavicle,  and 
divides  into  numerous  filaments,  some  of  which  surround 
the  a.\illary  artery,  others  descend  on  the  chest  and  are 
distributed  to  the  pectoral  muscles. 

The  posterior  thoracic  branch  is  furnished  by  the  sixth 
and  seventh  cervical  nerve  ;'it  descends  on  the  sides  of  the 
thorax,  and  is  distributed  to  the  serratus  magnus; 

The  supra  scapular  branch  is  supplied  by  the  5th  nerve  ; 
it  descends  obliquely  backwards  towards  the  upper  edge 
of  the  scapula,  passes  under  the  ligament  which  converts 
the  coracoid  notch  into  a foramen,  and  after  giving  a branch 
to  the  subscapularis  muscle,  it  passes  into  the  infra-spinatus 
fossa,  where  its  ramifications  are  lost  in  the  infra-spinatus 
and  teres  major  muscles. 

The  sub-scapular  branches  commence  at  variable  points 
of  the  brachial  plexus  ; they  descend  behind  the  axillary 
vessels  and  are  distributed  to  the  muscles  under  the 
scapula,  and  in  the  teres  major  and  minor. 

NERVES  OF  THE  ARM. 

INTERNAL  CUTANEOUS  NERVE. 

The  internal  cutaneous  nerve  is  the  smallest  of  the 
branches  which  terminate  the  brachial  plexus,  from  the 
lower  part  of  which  it  proceeds  ; namely,  from  the  last 
cervical  and  the  first  dorsal ; it  descends  along  the  internal 
surface  of  the  arm,  under  the  brachial  aponeurosis,  near 
the  basilic  vein,  and  divides  at  the  internal  condyle  of  the 
os  brachii  into  two  branches.  The  external  branch  passes 


NERVOUS  SYSTEM. 


105 


along  the  border  of  the  biceps  towards  the  wrist,  where  it 
is  distributed  to  the  integuments.  The  internal  branch 
descends  on  the  brachialis  internus,  supplies  the  integu- 
ments of  the  back  part  of  the  fore-arm,  and  finally  ter- 
minates at  the  back  of  the  hand  and  the  little  finger. 

EXTERNAL  CUTANEOUS  NERVE,  OR  MUSCULO-CUTANEOUS. 

The  external  cutaneous  nerve,  is  derived  from  the  fifth 
and  sixth  cervical  nerves  ; it  proceeds  through  the  fibres  of 
the  coraco-brachialis  muscle,  (from  which  circumstance  it 
is  named  the  perforans  casserii,)  and  descends  along  the 
anterior  part  of  the  arm,  between  the  biceps  and  brachialis 
internus,  towards  the  wrist,  where  it  divides  into  two 
branches  ; an  external,  which  sends  branches  to  the  back 
of  the  fingers  ; an  internal,  which  is  distributed  to  the 
thumb  and  the  palm  of  the  hand; — and  a multitude  of 
filaments  from  this  nerve  may  be  traced  to  the  fingers. 


VOL.  II. 


14 


106 


NERVOUS  SYSTEM. 


Fig.  30. 


Fig.  30,  exhibits  some 
of  the  principal  nerves  of 
the  front  of  the  arm. 

a,  b,  c,  d,  the  axillary 
plexus. 

e,  the  ulnar  or  cubital 
nerve. 

f,  the  median  nerve. 

g,  the  radial  nerve. 

h,  the  internal  cutane- 
ous nerve. 

i,  the  articular  nerve. 


NERVOUS  SYSTEM. 


107 


THE  MEDIAN  NERVE. 


The  median  nerve  is  the  largest  of  the  brachial  plexus  ; 
it  is  principally  formed  by  the  two  lower  cervical  and  the 
first  dorsal  nerves.  De- 
scending behind  the  in- 
ternal  part  of  the  biceps, 
on  the  inner  side  of  the 
brachial  artery,  and  dip- 
ping between  the  bra- 
chialis  internus  and  po- 
nator  teres,  it  descends 
along  the  fore-arm,  be- 
tween the  superficial  and 
deep  seated  flexor  mus- 
cles. It  then  proceeds 
under  the  annular  liga- 
ment of  the  carpus,  and 
divides  in  the  hand  into 
digital  filaments,  which 
are  distributed  to  the  fin- 
gers. Before  this  divi- 
sion, however,  it  furnish- 
es considerable  branches 
to  the  muscles  of  the 
fore-arm. 

Fig.  31,  exhibits  the 
distribution  of  the  prin- 
cipal branches  of  the 
median  nerve  on  the 
fore-arm. 

a,  the  trunk  of  the 
median  nerve. 


108 


NERVOUS  SYSTEM. 


h,  a branch  given  to  the  supinator  muscles. 

c,  a branch  to  the  interosseous  ligament,  and  to  the  flex- 
or profundus  muscle. 

d,  the  ulnar  nerve  cut  off. 

e,  the  palmar  branch  given  to  the  integuments  of  the 
hand. 

f,  a branch  to  the  pronator  muscles. 

ULNAR  NERVE. 

The  ulnar  nerve  proceeds  from  the  last  cervical  and  first 
dorsal  nerves,  and  descends  along  the  internal  border  of  the 
triceps,  supplying  this  muscle  and  the  upper  part  of  the 
fore-arm  with  numerous  filaments  ; then  passing  between 
the  inner  condyle  of  the  humerus  and  the  olecranon,  gives 
many  branches  to  the  flexor  carpi  ulnaris,  and  descends 
along  the  anterior  and  internal  part  of  the  fore-arm,  divid- 
ing near  the  wrist  into  two  branches,  the  palmar  and  the 
dorsal.  The  former  is  directed  on  the  outer  part  of  the 
tendon  of  the  flexor-carpi  ulnaris,  on  the  side  of  the  os 
pisiforrne,  and  divides  into  the  deep,  the  superficial,  the 
external,  and  the  internal  branches,  which  are  distributed 
to  the  fingers.  The  latter,  or  dorsal,  gains  the  internal  pari 
of  the  back  of  the  hand,  and  divides  into  internal  branches, 
which  are  extended  to  the  corresponding  surface  of  the 
middle,  the  ring  finger,  and  the  little  finger. 


NERVOUS  SYSTEM. 


109 


Fig.  32,  exhibits  the  dis- 
tribution of  the  principal 
branches  of  the  ulnar  nerve. 

a,  the  ulnar  nerve  perfo- 
rating the  heads  of  the  flex- 
or muscles. 

h,  c,  branches  distributed 
to  the  common  extensor  of 
the  fingers. 

d,  a branch  distributed  to 
the  interosseous  ligament. 

e,  a branch  distributed  to 
the  wrist  and  the  back  of  the 
hand. 


’H'  - V 


fig.  32. 


RADIAL  NERVE. 


The  radial  or  muscular  spiral  nerve,  has  the  same  deriva- 
tion as  the  preceding  ; it  descends  between  the  middle  and 
the  short  portions  of  the  triceps  muscle,  turns  round  the 
os  brachii  to  the  external  part  of  the  arm,  and  at  the  elbow 
joint  divides  into  two  branches ; the  anterior  which  de- 
scends between  the  two  supinator  muscles,  and  is  distribu- 
ted to  the  thumb,  and  the  inner  side  and  back  of  the  fore 


110 


NERVOUS  SYSTEM. 


finger,  and  the  outer  side  of  the  middle  finger.  Its  poste- 
rior branch  is  divided  into  filaments,  which  are  distributed 
to  the  superficial  muscles  of  the  fore-arm. 

CIRCUMFLEX  NERVE. 

The  circumflex,  or  articular  nerve,  is  usually  formed  by 
the  two  last  cervical  and  the  first  dorsal  nerve  ; it  descends 
in  front  of  the  subscapularis  muscle,  to  which  it  gives  a 
branch,  and  turns  backwards,  between  the  superior  part  of 
the  os  brachii  and  the  long  portion  of  the  triceps : it  is 
ultimately  distributed  to  the  internal  surface  of  the  deltoid 
muscle,  near  its  insertion  in  the  os  brachii. 

DORSAL  NERVES. 

The  dorsal  nerves,  or  those  which  are  transmitted  by  the 
intervertebral  foramina  of  the  dorsal  region,  like  the  cervi- 
cal nerves,  proceed  from  the  lateral  parts  of  the  spinal 
marrow  by  two  distinct  roots,  an  anterior  or  small,  and  a 
posterior  or  large,  separated  by  the  ligamentum  denticula- 
tum.  Beyond  the  intervertebral  foramen,  the  double  roots 
are  united  into  a single  trunk,  and  a small  gray  and  hard 
ganglion  is  formed  by  the  posterior  roots.  These  nerves 
divide  into  dorsal  and  intercostal  branches. 

The  dorsal  branches  pass  backwards  between  the  trans- 
verse processes  of  the  dorsal  vertebrae,  and  are  distributed 
to  the  muscles  and  integuments  of  the  back  and  loins. 

The  intercostal  branches,  near  their  commencement,  re- 
ceive a filament  from  each  thoracic  ganglion,  pass  outwards 
between  the  ribs,  covered  by  the  pleura,  as  far  as  the  angle 
of  these  bones,  where  they  are  found  between  the-  two 
strata  of  intercostal  muscles.  The  anterior  branch  of  the 


NERVOUS  SYSTEM. 


Ill 


second  follows  the  internal  surface  of  the  second  rib,  and 
sends  off  a brachial  filament,  which  pierces  the  external 
intercostal  muscle,  and  descends  along  the  posterior  and  in- 
ternal part  of  the  arm,  and  is  lost  at  the  elbow : this  is 
named  the  nerve  of  Wrisberg,  The  anterior  branches  of 
the  fourth  to  the  eleventh  dorsal  nerve,  proceed  along  the 
inferior  margin  of  the  corresponding  ribs,  and  are  distribu- 
ted to  the  muscles  and  the  integuments  of  their  different 
regions.  The  anterior  branch  of  the  twelfth,  at  its  com- 
mencement, communicates  by  a filament  with  the  first  lum- 
bar nerve,  and  is  afterwards  distributed  to  the  muscles  and 
the  integuments  of  the  abdomen. 

LUMBAR  NERVES. 

The  lumbar  nerves,  or  those  which  are  transmitted  by 
the  intervertebral  foramina  of  the  lumbar  vertebrae,  consist 
of  five  pair ; commencing  by  two  broad  fasciculi  of  fila- 
ments, which  the  older  writers  termed  cauda  equina,  from 
the  resemblance  they  bear  to  the  tail  of  a horse  ; especially 
when  the  nervous  fibres  are  unravelled,  and  separated  from 
each  other. 

The  anterior  branches  of  the  five  lumbar  nerves  form, 
by  their  union,  the  limb ar  plexus,  which  is  situated  behind 
the  psoas  muscle,  on  the  lateral  parts  of  the  bodies  of  the 
second,  third,  and  fourth  lumbar  vertebrae. 

FIRST  LUMBAR  NERVE. 

The  posterior  branch  of  this  nerve  is  distributed  to  the 
multifidus  spinae,  traverses  the  sacro-spinalis  muscle,  and 
passing  under  the  aponeuroses  of  the  abdominal  muscles, 
finally  ramifies  in  the  integuments  of  the  upper  part  of  the 
hip. 


112 


NERVOUS  SYSTEM. 


The  anterior  branch  receives  a communicating  filament 
from  the  lumbar  ganglia,  and  from  the  twelfth  dorsal  nerve, 
and  terminates  in  the  lumbar  plexus. 

SECOND  LUMBAR .NERVE. 

The  posterior  branch  of  this  nerve  takes  nearly  the  same 
course  as  the  former,  and  is  expanded  by  a great  number 
of  subdivisions  on  the  upper  and  back  part  of  the  thigh. 

The  anterior  branch  has  extensive  communications  with 
the  lumbar  ganglia,  the  anterior  branches  of  the  first  hand 
second  pairs  of  the  lumbar  region,  and  with  the  lumbo- 
abdominal  plexus.  ^ 

THIRD  LUMBAR  NERVE. 

The  posterior  branch  is  distributed  precisely  in  the  same 
manner  as  the  former. 

The  anterior  branch  communicates  with  the  second  and 
the  fourth  lumbar  nerves,  giving  contributions  as  the  pre- 
ceding. 

EOURTH  AND  FIFTH  LUMBAR  NERVES. 

The  posterior  and  anterior  branches  have  a similar  distri- 
bution to  those  just  described ; some  filaments,  however, 
of  the  latter  are  continued  into  the  pelvis,  to  unite  with 
the  sciatic  plexus. 


NERVOUS  SYSTE3I. 


113 


LUMBO-ABDOMINAL,  OR  LUMBAR  PLEXUS. 

This  plexus  is  formed  by  the  union  of  the  anterior 
branches  of  the  five  lumbar  nerves  ; it  is  situated  on  the 
lateral  parts  of  the  bodies  of  the  second,  third,  and  fourth 
lumbar  vertebrae,  behind  the  psoas  magnus.  It  terminates 
in  the  musculo-cutajieous,  the  genito-crural,  the  crural,  the 
obturator,  and  the  lumbosacral  nerves. 


MUSCULO-CUTANEOUS  BRANCHES. 

These  branches  are  commonly  three  in  number;  1st,  the 
superior,  proceeding  from  the  first  lumbar  nerve,  descends 
on  the  quadratus  lumborum  as  far  as  the  crest  of  the  ilium, 
pierces  the  transversalis  muscle,  and  ramifying  in  the  mus- 
cles and  integuments  of  the  abdomen,  and  extending  to 
the  abdominal  ring,  is  distributed  to  the  groin,  the  pubic 
region,  the  scrotum  in  the  male,  and  the  labia  pudendi  in 
the  female.  2d,  the  middle  branch  descends  on  the  outer 
margin  of  the  psoas  muscle,  perforates  the  transversalis 
and  is  distributed  to  the  cellular  tissue  of  the  abdomen  ; 
one  filament  is  transmitted  to  the  superior  part  of  the  scro- 
tum. 3d,  the  inferior  branch  extending  from  the  second 
lumbar  nerve,  and  passing  out  of  the  pelvis,  between  the 
superior  and  the  inferior  spinous  processes  of  the  ilium,  is 
distributed  to  the  posterior  superior  part  of  the  thigh.  An 
internal  filament  pierces  the  fascia  lata  and  descends  to  the 
external  part  of  the  knee. 

VOL.  JF.  15 


114 


NERVOUS  SYSTEM. 


GENITO-CRUKAL  NERVE. 

This  nerve  proceeds  from  the  first  lumbar  nerve ; it  de- 
scends in  tlie  substance  of  the  psoas  muscle,  and  afterwards 
divides  into  an  internal  branch,  which  accompanies  the 
spermatic  cord ; and  an  external,  which,  at  the  crural  arch, 
is  distributed  in  a multitude  of  filaments  in  the  subcutane- 
ous cellular  tissue. 


CRURAL  NERVE. 

This  nerve  commences  at  the  first  four  lumbar  nerves  ; 
it  passes  out  of  the  abdomen  under  the  crural  arch,  on  the 
outer  side  of  the  femoral  artery,  and  then  divides  into  deep 
seated  and  superficial  branches. 

1st.  The  superficial  branches  perforate  the  fascia  lata, 
and  are  distributed  in  the  integuments  of  the  anterior  and 
inner  part  of  the  thigh,  descending  as  far  as  the  superior 
part  of  the  leg. 

2d.  The  deep  seated  branches  divide  into  numerous  fila- 
ments, which  are  distributed  to  the  iliacus,  the  sartorius, 
and  the  triceps  extensor  cruris  muscles.  The  internal 
branches  supply  the  muscles  on  the  corresponding  part  of 
the  thigh  ; one  of  these,  more  conspicuous  than  the  other 
branches,  termed  the  internal  saphena  nerve,  accompanies 
the  vena  saphena  in  all  its  divisions  to  the  great  toe. 


NERVOUS  SYSTEM. 


115 


Fig.  33,  exhibits  the  prin- 
cipal nerves  of  the  front  of 
the  thigh. 

a,  a branch  of  the  first 
lumbar  nerve. 

b,  a branch  of  the  second 
lumbar  nerve. 

c,  the  crural  nerve,  vi^ith 
its  divisions  into  the  branches 
which  supply  the  front  of  the 
thigh. 

d,  a branch  to  the  triceps 
extensor  cruris  muscle. 

e,  e,  the  saphena  nerve, 
sent  from  the  crural  nerve  to 
the  inner  part  of  the  leg. 

/,  the  external  cutaneous 
nerve. 

g,  the  femoral  artery. 

A,  the  anterior  obturator 
nerve. 


Fig.  33. 


OBTURATOR  NERVE. 


This  nerve  issues  principally  from  the  second,  third,  and 
sometimes  from  the  fourth,  lumbar  nerves  ; it  descends  on 
the  inner  margin  of  the  psoas  muscle,  gives  a branch  to 
the  obturator  muscles,  traverses  the  obturator  foramen, 


116 


NERVOUS  SYSTEM. 


and  between  the  pectineus  and  first  adductor,  divides  into 
two  branches.  1st.  Its  anterior  branch,  distributed  to 
the  little  adductor  and  vastus  internus.  2d.  Its  pos- 
terior branch  to  the  great  adductor  and  external  obturator 
muscles. 


LUMBO-SACRAL  NERVE. 

This  nerve  is  derived  from  the  fourth  and  fifth  lumbar 
nerves  ; it  descends  into  the  pelvis,  and  unites  with  the 
sciatic  plexus.  In  its  course  it  furnishes  a single  branch, 
which  is  the  glutaal  nerve. 


GLUT.®AL  NERVE. 

This  nerve  derives  some  roots  from  the  sciatic  plexus  ; 
it  passes  out  of  the  sciatic  notch,  and  divides  into  a multi- 
tude of  branches,  which  are  distributed  to  the  glutsei  mus- 
cles, the  perineum  and  the  subcutaneous  cellular  tissue  at 
the  back  of  the  thigh. 


SACRAL  NERVES. 

The  sacral  nerves  issue  from  the  sacral  canal ; they  con- 
sist of  five  or  six  pairs,  derived  from  the  inferior  part  of  the 
spinal  cord.  Their  posterior  branches  supply  the  various 
muscles  in  their  vicinity ; while  the  anterior  branches  of 
the  first  four  sacral,  with  those  of  the  fifth  lumbar,  form 
the  SACRAL  or  sciatic  plexus.  These  branches,  again 
uniting,  form  a large  nerve,  termed  the  sciatic  nerve.  It 
also  furnishes  the  hemorrhoidal,  the  vesical,  the  uterine, 
and  the  vaginal  nerve  (which  are  small  and  interlacing 


NERVOUS  SYSTEM. 


117 


with  each  other)  ; and  the  inferior  gluteal  and  pudic, 
which  are  distributed  to  those  parts  the  several  names  in- 
dicate. 

SCIATIC  NERVE. 

The  sciatic  nerve  terminates  the  plexus  of  the  same 
name,  and  is  the  largest  of  all  the  nerves  of  the  body  ; it 
passes  out  of  the  pelvis  by  the  sciatic  notch,  between  the 
pyramidalis  and  superior  gemellus,  and  descends  along  the 
posterior  part  of  the  thigh  as  far  as  the  ham,  where  it  di- 
vides into  two  branches,  termed  the  popliteal.  As  the 
sciatic  nerve  proceeds  down  the  leg,  it  furnishes  filaments 
to  the  adjacent  muscles,  and  to  the  integuments. 

EXTERNAL  POPLITEAL  NERVE. 

This  nerve  has  also  the  name  of  fibular,  or  peroneal 
nerve ; it  descends  behind  the  external  condyle  of  the  fe- 
mur, and  passes  between  the  fibula  and  the  peroneus 
longus  muscle,  and  divides  into  the  musculo-cutaneous, 
and  the  anterior  tibial.  The  musculo-cutaneous , or  external 
fibular  nerve,  descends  between  the  peroneus  longus,  and 
the  extensor  digitorum  pedis,  and  afterwards  between  this 
latter  and  the  peroneus  brevis.  Towards  the  middle  of 
the  leg  it  becomes  superficial,  and  divides  near  the  foot 
into  filaments,  which  are  distributed  to  the  back  of  the 
foot  and  to  the  toes. 

The  anterior  tibial  nerve  descends  in  front  of  the  inter- 
osseous ligament,  ramifies  in  the  extensor  brevis  digitorum 
pedis,  and  gives  filaments  to  the  first  two  toes. 


118 


NERVOUS  SYSTEM. 


INTERNAL  POPLITEAL  NERVE. 

This  nerve  is  larger  than  the  preceding,  and  descends 
into  the  ham,  passing  behind  the  articulation,  and  between 
the  heads  of  the  gastrocnemii  and  the  popliteus  muscles, 
then  between  the  latter  and  the  soleus  muscle  ; there  it 
passes  through  the  arched  aperture  which  that  muscle  pre- 
sents, and  takes  the  name  of  the  tihial  nerve.  This  nerve 
descends  between  the  soleus  and  tibialis  posticus  posteri- 
orly, and  the  flexor  longus  digitorum  pedis  anteriorly,  and 
is  closely  connected  with  the  posterior  tibial  artery  : — be- 
neath the  os  calcis  it  divides  into  the  external  and  internal 
plantar  nerves.  The  tibial  nerve  furnishes,  above  the  ex- 
ternal condyle  of  the  femur,  the  external  sa'pliena  nerve. 
In  the  ham  it  supplier  filaments  to  the  muscles  of  the 
superior  part  of  the  leg,  and  to  the  articulation  of  the 
knee ; to  the  interosseous  ligament  and  to  the  anterior 
muscles  of  the  leg.  Near  the  inner  malleolus,  it  sends  a 
filament  to  the  sole  of  the  foot. 

The  internal  plantar  hranch  proceeds  directly  forwards 
above  the  adductor  proprius  pollicis  pedis,  and  is  distri- 
buted to  the  internal  part  of  the  foot  and  to  the  toes. 

The  external  plantar  branch  is  directed  forwards  and  out- 
wards, and  is  distributed  to  the  external  border  of  the  foot 
and  to  the  interosseous  muscles. 


NERVOUS  SYSTEM. 


119 


Fig.  34j  exhibits  the  princi- 
pal nerves  of  the  back  part  of 
the  thigh. 

a,  the  sciatic  nerve,  passing 
out  of  the  pelvis. 

b,  the  posterior  superior  cu- 
taneous nerve. 

c,  the  trunk  of  the  sciatic 
nerve,  sending  branches  to  the 
muscles  of  the  back  part  of  the 
thigh. 

d,  the  division  of  this  lierve 
into, — 

e,  the  tibial  nerve,  and, — 

/,  the  fibular  nerve. 


Fig.  34. 


120 


NERVOUS  SYSTEM. 


CHAP.  II. 

GANGLIONIC  DEPARTMENT  OF  THE  NERVOUS  SYSTEM. 


It  has  been  before  remarked  in  this  work,  that  in  the  in- 
fancy of  anatomy  the  term  “ gangfion”  was  used  to  denote 
a swelling  in  the  theca3  of  tendons,  and  even  at  the  present 
day  it  is  not  unfrequently  employed  in  the  same  sense.  It 
was  subsequently  applied  to  the  knotted  appearance  pre- 
sented by  certain  nerves,  but  of  late  years  a considerable 
latitude  has  been  given  to  its  signification  by  Gall  and 
Spurzheim,  who  include  within  its  comprehension,  the 
several  masses  of  cineritious  substance  inclosed  within  the 
medulla  and  brain,  and  which  according  to  their  theory, 
are  considered  “ ganglia  of  increase”  to  the  formative  fibres 
of  the  cerebral  hemispheres.  (0°=The  term  “ formative 
fibres”  will  be  explained  at  the  termination  of  the  article 
on  the  nervous  system. 

Nervous  ganglia  may  be  divided  into  two  orders.  1. 
Those  observable  on  the  posterior  roots  of  the  cerebro- 
spinal nerves,  including  that  of  the  fifth  nerve  ; 2.  The 
ganglia  of  the  sympathetic. 

The  ganglia  are  small  nervous  centres,  (see  Fig.  35,  and 


3G,)  which  some  anatomists  have  designated  by  the  appel- 
lation of  diminutive  brains.”  They  extend  from  the  cra- 


Fig.  35. 


Fig.  36. 


NEUVOUS  SYSTEM. 


121 


nium  to  the  pelvis,  mostly  lying  along  the  vertebral  column, 
and  presenting  a series  connected  by  nervous  filaments, 
each  ganglion  being  considered  by  most  physiologists  as  a 
special  centre  of  nervous  influence. 

The  forms  of  the  ganglia  are  very  irregular ; in  general 
they  are  somewhat  round  ; occasionally  they  are  elongated  ; 
in  other  instances  they  are  of  a semilunar  form,  as  that 
which  bears  this  name.  In  general  all  their  forms,  as  I 
have  just  noticed,  are  remarkably  irregular. 

Each  ganglion  transmits  nerves  upwards  and  downwards 
to  the  ganglia  which  are  contiguous  ; and  other  nerves  to 
the  cerebral  or  spinal  nerves.  The  greater  part,  however, 
of  the  nervous  filaments  radiating  from  the  ganglia  are  in- 
terwoven, in  the  form  of  a net-work  or  plexus ; the  most 
remarkable  of  which  is  the  solar  plexus,  which  is  formed 
by  the  innumerable  nerves  proceeding  from  the  semilunar, 
the  hypogastric,  and  the  cardiac  ganglia.  The  filaments 
of  the  ganglia,  as  it  were,  exchange  their  connections  and 
their  direction,  and  form  angles  and  meshes  so  intricate 
that  it  is  not  possible  to  distinguish  anything  more  than  a 
mass  of  nerves. 

The  ganglia  are  amply  supplied  with  blood-vessels  which 
penetrate  them  on  all  sides,  ramifying  on  their  surface  and 
uniting  in  their  interior. 

The  cerebro-spinal  department  of  the  nervous  system  is 
the  immediate  agent  of  the  will,  whilst  the  ganglionic  de- 
partment presides  altogether  out  of  the  influence  of  the  will 
of  the  individual.  Thus,  for  example,  the  heart  contracts 
without  our  possessing  the  power  of  accelerating  or  retard- 
ing its  movements,  in  any  sudden  way,  according  to  our 
will ; the  stomach  in  like  manner  acts  on  the  aliments,  and 
digests  them  without  our  being  able  to  exercise  any  control 
over  its  operations  ; and  for  this  reason,  these  organs  are 
under  the  direction  of  the  ganglionic  department  of  the 
nervous  system. 


VOL.  II. 


16 


122 


NERVOUS  SYSTEM. 


PARTICULAR  GANGLIA. 

GANGLIA  OF  THE  HEAD. 

LENTICULAR  GANGLION. 

The  lenticular  ganglion  is  situated  on  the  external  side 
of  the  optic  nerve,  near  its  entry  into  the  orbit ; its  form  is 
oblong  and  very  small.  Posteriorly,  it  receives  a filament 
from  the  nasal  branch  of  the  ophthalmic,  and  one  from  the 
third  nerve  ; anteriorly,  it  furnishes  the  ciliary  nerves. 

The  ciliary  nerves  are  very  delicate,  and  are  divided  into 
two  fasciculi ; the  superior  fasciculus  is  formed  of  six  fila- 
ments, which  extend  to  the  globe  of  the  eye  above  the 
optic  nerve.  The  inferior  fasciculus  is  composed  of  eight 
or  ten  nervous  filaments,  which  proceed  on  the  outer  and 
inferior  part  of  the  optic  nerve.  , 

These  nerves,  consisting  of  from  twelve  to  seventeen, 
pass  obliquely  through  the  sclerotica,  and  proceed  in  a 
parallel  direction  between  the  latter  membrane  and  the 
choroid,  and,  reaching  the  ciliary  circle,  each  filament 
subdivides  and  is  extended  to  the  ciliary  ligament  and 
the  iris. 

SPHENO-PALATINE  GANGLION. 

This  ganglion,  denominated  also  the  ganglion  of  Meckel, 
is  a small  triangular  reddish  body  ; it  is  not  very  readily 
discovered,  being  concealed  in  the  adipose  cellular  tissue 
of  the  pterygo-maxillary  fissure.  This  ganglion  furnishes 
the  following  branches  : — 

The  ascending  branches,  two  in  number,  which  pass  up- 
wards, and  join  the  superior  maxillary,  or  second  branch  of 


NERVOUS  SYSTEM.  123 

the  fifth  pair,  previously  to  its  entrance  into  the  infra-orbi- 
tar  canal. 

The  spheno-palatine  nerves,  varying  in  number  from  three 
to  five  ; they  pass  into  the  nasal  fossa  by  the  spheno-pala- 
tine foramen.  Two  or  three  filaments  ramify  on  the  con- 
cave surface  of  the  superior  turbinated  bone,  and  in  the 
corresponding  meatus  ; some  extend  to  the  middle  turbina- 
ted bone,  and  others  are  distributed  to  the  posterior  part 
of  the  septum  narium.  The  most  considerable  filament, 
termed  the  naso-palatine,  is  directed  to  the  superior  part  of 
the  septum,  and  terminates  in  the  naso-palatine  ganglion. 

The  palatine  nerves  are,  1st,  the  great  or  inferior  pala- 
tine, which  furnishes  a filament  to  the  middle  and  inferior 
turbinated  bones  ; it  afterwards  enters  the  posterior  pala- 
tine canal,  and  before  its  exit  gives  another  filament  to  the 
nasal  fossae,  which  is  lost  on  the  ascending  process  of  the 
superior  maxillary  bone.  Other  filaments  are  distributed 
to  the  velum  palati,  the  arch  of  the  palate,  the  alveoli,  and 
the  gums. 

2d.  The  middle  palatine  nerves,  which  are  distributed  to 
the  amygdalae  and  to  the  velum  palati. 

3d.  The  lesser  palatine  nerves,  which  are  situated  be- 
tween the  external  pterygoid  muscle  and  the  superior  max- 
illary bone  ; they  are  destined  for  the  tonsils  and  the  mucous 
follicles  of  the  membrane  of  the  palate. 

4th.  The  Vidian  nerve  leaves  the  spheno-palatine  gangli- 
on and  enters  the  pterygoid  canal,  giving  filaments  to  the 
adjacent  parts ; then  divides  into  two  branches,  1st,  the 
inferior  or  carotid  branch,  which  descends  into  the  carotid 
canal,  and  unites  with  the  superior  cervical  ganglion.  2d. 
The  superior  branch,  which  takes  rather  a complicated 
course,  enters  the  cranium  between  the  petrous  portion  of 
the  temporal  and  the  sphenoid  bones,  and  is  directed 
backwards  and  outwards  on  the  superior  surface  of  the 
former  bone,  where  it  is  lodged  in  a small  groove  cov- 


124 


NERVOUS  SYSTEM. 


ered  by  the  inferior  maxillary  nerve  and  the  dura  mater ; 
it  then  passes  with  a small  artery  into  the  hiatus  fallopii, 
and,  on  arriving  at  the  aqueduct  of  Fallopius,  is  found  in 
apposition  with  the  facial  nerve.  It  then  penetrates  the 
cavity  of  the  tympanum,  where  it  is  denominated  the  corda 
tympani ; above  the  tensor  tympani  it  enlarges,  and  is  di- 
rected downwards  and  forwards,  passes  out  of  the  glenoid, 
or  Glasserian  fissure,  and  is  attached  to  the  lingual  branch 
of  the  inferior  maxillary  nerve.  Opposite  the  submaxillary 
gland  it  separates  from  it  to  proceed  to  the  ganglion  of  the 
same  name. 


Fig.  37. 


Fig.  .37,  exhibits  the  course  of-the  corda  tympani,  on  the 
left  side. 

a,  the  facial  nerve  in  the  aqueduct  of  Fallopius. 
h,  the  Vidian  nerve  communicating  with  the  facial  in  the 
aqueduct  of  Fallopius. 

c,  a filament  of  the  facial  given  to  the  laxator  tympani. 

d,  a filament  given  to  the  muscle  of  the  stapes. 

e,  the  corda  tympani,  separating  from  the  facial,  passing 


NERVOUS  SYSTEM. 


125 


through  the  cavity  of  the  tympanum,  and  uniting  with,  g, 
the  inferior  maxillary  nerve. 

Besides  those  before  described,  the  following  ganglia  are 
met  with  in  the  head,  namely  — 

The  cavernous  ganglion,  situated  on  the  outer  side  of  the 
internal  carotid  artery  in  the  cavernous  sinus. 

The  naso-palatine  ganglion,  situated  in  the  anterior  pala- 
tine foramen. 

The  submaxillary  ganglion,  occurring  on  a level  with  the 
submaxillary  gland,  and  apparently  formed  by  the  superior 
filament  of  the  Vidian  nerve. 


GANGLIA  OF  THE  NECK. 

supehior,  or  great  cervical  ganglion.  Fig.  28,  a. 

This  ganglion  is  found  under  the  angle  of  the  inferior 
maxilla,  and  is  remarkable  for  its  size  and  the  regularity  of 
its  occurrence ; it  is  of  a reddish  gray  color  and  is  inti- 
mately united  to  the  pneumo-gastric  and  hypoglossal 
nerves.  It  lies  on  the  rectus  anticus  muscle,  concealed  by 
the  jugular  vein  and  carotid  artery.  A number  of  nervous 
filaments  issue  from  it,  which  are  distinguished  into  supe- 
rior, inferior,  external,  and  anterior. 

The  superior  or  ascending  filaments  ascend  into  the 
carotid  canal,  and  unite  with  the  superior  filament  of  the 
Vidian  nerve,  with  the  sixth  pair  in  the  cavernous  sinus, 
with  a filament  from  the  glosso-pharyngeal,  and  by  other 
filaments  with  the  ophthalmic  and  nasal  branches. 

The  inferior  or  descending  filaments  pass  in  front  of  the 
anterior  recti  and  longus  colli  muscles,  covered  by  the 
carotid  artery,  the  jugular  vein,  the  pneumo-gastric,  and 
the  hypoglossal  nerves,  and  terminate  on  a level  with  the 
fifth  or  sixth  vertebra  in  the  middle  cervical  ganglion. 


126 


NERVOUS  SYSTEM. 


Filaments  from  the  superior  ganglion  unite  with  the  ex- 
ternal laryngeal  nerve,  and  others  which  enter  the  thorax 
concur  in  forming  the  cardiac  plexus.  The  external,  in- 
ternal, and  anterior  filaments,  communicate  with  nerves  in 
their  vicinity  ; thus  the  first  unites  with  the  cervical  nerves, 
the  second  with  the  pneumo-gastric,  forming  the  pharyn- 
geal plexus ; and  the  third  with  the  pneumo-gastric  and 
the  facial  nerves,  forming  a plexus  upon  the  primitive 
carotid  : finally,  the  latter  filaments  of  the  superior  cervical 
ganglion  unite  to  form  the  superior  cardiac  nerve. 


MIDDLE  CERVICAL  GANGLION.  Fig.  28,  h. 

This  ganglion  varies  extremely  in  size,  and,  indeed,  is 
not  constantly  found  ; it  is  situated  opposite  the  fifth  or 
sixth  cervical  vertebra,  and  before  the  carotid  artery  and 
jugular  vein.  Its  anterior  filaments  form  the  middle  car- 
diac nerves. 


INFERIOR  CERVICAL  GANGLION. 

This  ganglion  is  frequently  continuous  with  the  middle 
cervical  ganglion  ; it  is  situated  behind  the  vertebral  ar- 
tery, between  the  transverse  process  of  the  seventh  ver- 
tebra, and  the  neck  of  the  first  rib.  Numerous  filaments 
issue  from  this  ganglion,  which  unite  with  the  cervical 
nerves,  the  first  thoracic  ganglion,  and  the  inferior  cardiac 
nerves. 


CARDIAC  NERVES.  Fig.  28,  71. 

These  nerves  are  particularly  destined  to  supply  the 


NERVOUS  SYSTEM. 


127 


heart : there  are  three  on  each  side,  which  terminate  in  the 
cardiac  plexus. 

The  superior  cardiac  nerves,  on  the  right  side,  are  formed 
by  five  or  six  filaments  which  proceed  from  the  superior 
cervical  ganglion  ; they  descend  on  the  side  of  the  trachea, 
penetrate  the  thorax  behind  the  subclavian  vein  and  re- 
ceive filaments  from  the  inferior  cervical  ganglion,  and  the 
recurrent  nerve  of  the  pneumo-gastric.  Those  of  the  left 
side  are  situated  between  the  primitive  carotid  and  the  sub- 
clavian arteries,  and  proceed  on  the  aorta  to  unite  with  the 
inferior  cardiac  nerves. 

The  middle  cardiac  nerves,  on  the  right  side,  proceed  by 
five  or  six  filaments  from  the  middle  cervical  ganglion  ; 
these  descend  near  the  primitive  carotid,  uniting  with  the 
recurrent,  and  terminating  in  the  cardiac  plexus.  That  of 
the  left  side  receives  its  principal  filament  from  the  inferior 
cervical  ganglion,  and  descends  behind  the  subclavian  ar- 
tery and  the  arch  of  the  aorta. 

The  inferior  cardiac  nerves,  on  the  right  side,  descend 
from  the  inferior  cervical  ganglion,  and  proceed  on  the 
anterior  part  of  the  arch  of  the  aorta,  as  far  as  the  cardiac 
plexus. 

The  middle,  and  the  inferior  cardiac  nerves,  on  the  left 
side,  are  united  into  a single  trunk. 


CARDIAC  PLEXUS,  OR  GANGLION.  Fig.  28,  S. 

The  cardiac  plexus  is  situated  behind  the  arch  of  the 
aorta,  and  consists  of  a central  point  of  union  of  the  car- 
diac nerves,  a great  number  of  which  issue  from  it,  and 
others  are  connected  with  it  in  every  direction  : some  ram- 
ify on  the  aorta ; others  terminate  in  the  pulmonary  plexus  ; 
several  are  distributed  to  the  pulmonary  artery  ; and  a con- 
siderable nerve  interlaces  its  filaments  in  the  direction  of 


128 


NERVOUS  SYSTEM. 


the  posterior  coronary  artery,  forming  the  coronary  plexus. 
Filaments  also  proceed  in  the  direction  of  the  anterior 
coronary  artery,  and  are  therefore  denominated  the  anterior 
coronary  plexus. 


THORACIC  GANGLIA. 

These  ganglia  are  smaller  than  the  cervical  ganglia  ; — 
there  are  twelve  on  each  side,  disposed  in  the  same  line  in 
front  of  the  head  of  each  rib.  Their  form  and  size  resem- 
ble grains  of  barley  ; they  communicate  by  vertical  fila- 
ments with  each  other,  and  furnish  also  external  and 
internal  filaments  : the  former  unite  with  each  of  the 
branches  of  the  dorsal  nerves,  at  the  point  of  their  exit 
from  their  foramina  ; the  latter  concur  in  the  formation  of 
the  splanchnic  nerves. 


SPLANCHNIC  NERVES. 

There  are  two  splanchnic  nerves  on  each  side,  distin- 
guished into  the  great  and  small. 


GREAT  SPLANCHNIC  NERVE. 

This  nerve  is  connected  with  the  internal  part  of  the 
sixth,  seventh,  eighth,  ninth,  and  sometimes  the  tenth 
thoracic  ganglia,  by  filaments  which  descend  on  the  sides 
of  the  vertebral  column,  and  unite  into  a single  trunk,  on  a 
level  with  the  eleventh  dorsal  vertebra : this  nervous  cord 
enters  the  abdomen,  passes  behind  the  stomach,  and  ter- 
minates in  the  semilunar  ganglion. 


NERVOUS  SYSTEM. 


129 


SMALL  SPLANCHNIC  NERVE. 

This  nerve  is  formed  of  two  branches  from  the  tenth 
and  the  eleventh  thoracic  ganglia ; these  branches  unite  into 
a small  cord  on  the  twelfth  dorsal  vertebra,  enter  the  abdo- 
men, and,  communicating  with  the  former,  terminate  in  the 
renal  ganglion. 

GANGLIA  OF  THE  ABDOMEN. 

SEMILUNAR  GANGLIA  AND  SOLAR  PLEXUS. 

The  semilunar  ganglia  are  two  in  number,  situated  on 
each  side  of  the  aorta,  on  a level  with  the  coeliac  artery ; 
they  are  larger  than  any  other  ganglia,  and  have  a form 
somewhat  corresponding  to  the  name.  The  superior  and 
external  extremity  of  each  ganglion  receives  the  great 
splanchnic  nerves  ; by  the  inferior  they  form  a communi- 
cation with  each  other.  The  two  semilunar  ganglia  are 
surrounded  by  a multitude  of  other  smaller  ganglia,  com- 
municating with  them  by  short  filaments,  which  issue  from 
their  circumference  ; and  the  secondary  ganglia  also  are 
united  to  each  other  by  very  numerous  filaments,  which 
form  areolae.  It  is  this  remarkable  assemblage  of  ganglia, 
and  interlacing  of  nervous  filaments,  that  constitutes  the 

SOLAR  PLEXUS. 

The  plexus  just  named,  appears  to  be  particularly  des- 
tined for  the  aorta,  being  distributed  to  all  its  divisions, 
and  following  all  its  immediate  branches  with  a correspond- 
ing number  of  secondary  plexuses,  such  as, — 

1.  The  sub-diaphragmatic  plexus,  which  is  composed  of 
a small  number  of  filaments,  which  unite  with  the  phrenic 
nerve  and  are  distributed  to  the  diaphragm. 

VOL.  II.  17 


130 


NERVOUS  SYSTEM. 


2.  The  caliac  plexus  is  merely  a prolongation  of  the 
solar  ple.xus,  upon  the  triple  division  of  the  coeliac  artery ; 
— it  is  composed  of  several  ganglia,  varying  in  form  and 
size. 

3.  Tlie  hepatic  plexus  is  associated  with  the  hepatic 
artery  and  the  vena  portcE  ; — it  follows  their  principal 
divisions. 

4.  The  splenic  plexus  follows  the  course  of  the  splenic 
artery,  and  is  distributed  to  the  spleen. 

5.  The  superior  mesenteric  plexus  descends  with  the  su- 
perior mesenteric  artery,  and  forms  a web  of  great  extent, 
the  filaments  of  which  are  distributed  to  the  lymphatic 
glands  of  the  mesentery,  and  follow  the  ramifications  of  the 
artery,  so  as  to  cover  the  whole  surface  of  the  small  intes- 
tines. This  plexus  also  furnishes  nerves  to  the  ascending 
colon  and  coecum. 

6.  The  inferior  mesenteric  plexus  accompanies  the  infe- 
rior mesenteric  artery,  enters  the  iliac  mesocolon,  and  is 
distributed  to  the  adjacent  parts. 

7.  The  renal  plexus  commences  by  several  ganglia,  situ- 
ated on  the  renal  artery,  and  is  distributed  to  the  substance 
of  the  kidney. 

8.  The  surrenal  plexus  is  found  at  the  commencement 
of  the  capsular  artery,  and  supplies  the  part  which  the  name 
implies. 

9.  The  spermatic  plexus  descends  from  the  renal,  and 
follows  the  direction  of  the  spermatic  artery,  to  the  testicle 
in  the  male,  and  to  the  ovarium  and  the  Fallopian  tube  in 
the  female. 

THE  LUMBAR  GANGLIA. 

These  ganglia  are  situated  on  the  anterior  and  lateral 
parts  of  tiic  bodies  of  the  lumbar  vertebrae  : they  are  com- 


NERVOUS  SYSTEM. 


131 


monly  five  in  number  on  each  side,  and  have  communica- 
ting nervous  branches,  and  externa]  and  internal  filaments, 
which  contribute  to  supply  the  adjacent  organs,  and  are 
united  with  the  sacral  ganglia. 


THE  SACRAL  GANGLIA. 

There  are  three  or  four  of  these  ganglia  found  on  each 
side  of  the  anterior  foramina  of  the  sacrum ; they  commu- 
nicate with  the  lumbar  ganglia,  and  contribute  to  form  the 
hypogastric  plexus. 


HYPOGASTRIC  PLEXUS. 

This  plexus  is  composed  of  numerous  filaments  from  the 
vesical,  uterine,  vaginal,  and  haemorrhoidal  nerves  of  the 
sciatic  plexus.  The  hypogastric  plexus  distributes  its  ram- 
ifications to  the  organs  of  generation  (within  the  pelvis), 
to  the  os  coccygis,  and  to  the  rectum. 


132 


NERVOUS  SYSTEM. 


Fig.  38. 


Fig.  38,  exhibita  some  of  the  principal  nervous  ganglia 
and  plexuses  of  the  thorax  and  abdomen,  on  the  left  side, 
and  the  pneumo-gastric  nerve,  on  the  same  side. 
a,  a,  thoracic  ganglia^ 
h,  the  pneumo-gastric  nerve. 

c,  a branch  of  the  former,  called  the  inferior  laryngeal 
or  recurrent,  curving  round  the  arcli  of  the  aorta. 


NERVOUS  SYSTEM. 


133 


d,  the  cEsophageal  plexus. 

e,  the  pericardium.  /,  the  lungs. 

r,  the  pulmonary  plexus. 

g,  the  diaphragm.  h,  the  spleen. 

i,  the  stomach. 

The  two  last  named  organs  are  turned  to  the  opposite 
side  to  shew  the  distribution  of  the  nerves. 

Tc,  the  kidney.  I,  the  abdominal  aorta. 

VI,  the  semilunar  ganglion,  and  solar  plexus,  the  latter 
radiating  to  all  the  divisions  of  the  aorta, 
n,  the  splenic  plexus.  o,  the  pancreas. 

p,  p,  p,  the  lumbar  ganglia. 

q,  the  obturator  nerve. 


THE  TERM  GREAT  SYMPATHETIC  NERVE. 

After  studying  this  department  of  the  nervous  system, 
we  can  see  the  reason  why  it  is  usually  denominated,  the 
great  sympathetic  nerve.  It  is  in  fact  a collection  of  filaments 
from  every  nerve  in  the  animal  fabric,  which  join  each  other 
at  the  adjacent  ganglia.  It  seems  to  spring  from  the 
sixth  nerve,  and  from  the  Vidian  branch  of  the  fifth,  and 
is  reinforced  by  filaments  from  the  seventh,  eighth,  ninth, 
and  all  the  spinal  nerves,  to  the  lumbar  region,  and  termi- 
nates in  the  pelvis. 

This  name,  which  has  been  given  to  the  ganglia  and 
their  nervous  radiations,  expresses  the  conviction  of  anato- 
mists, that  its  office  is  to  associate  the  affections  of  differ- 
ent parts.  And  we  cannot  doubt  that  this  department 
directs  and  controls  the  actions,  and  endows  organic  life, 
or  the  parts  within,  with  its  due  sensibilities  ; the  visceral 
sensations  are  always  involuntary ; they  are  generally 
vague,  confused,  and  usually  more  or  less  fugitive,  and 
do  not,  for  any  length  of  time,  become  fixed  in  the  mind. 


134 


NERVOUS  SYSTEM. 


If  our  internal  organs  act  according  to  the  ordinary  laws 
of  organization,  the  sensations  which  arise  from  them  are 
agreeable,  and  the  healthy  actions  may  give  us  the  most 
vivid  pleasure  ; but  if  the  actions  of  our  functions  are  in- 
terrupted, if  our  organs  are  wounded  or  diseased,  the  in- 
ternal sensations  are  painful,  and  according  to  the  disorder- 
ed state,  or  the  injury,  they  assume  a different  character. 


FORMATIVE  FIBRES  OF  THE  BRAIN  ACCORDING  TO  GALL 
AND  SPURZHEIM. 

Having  completed  the  anatomy  of  the  nervous  system 
as  usually  described  in  elementary  treatises  on  the  subject, 
it  may  not  be  considered  superfluous  to  give  briefly  the 
views  of  Drs  Gall  and  Spurzheim,  relative  to  the  manner 
in  which  the  cerebral  hemispheres  are  formed.  The  fol- 
lowing appears  to  be  the  simplest  exposition,  and  is  select- 
ed from  recent  writers.  The  cerebral  hemispheres  are 
considered  by  the  above  anatomists  as  resulting  from  an 
expansion  of  the  fibres  of  the  medulla ; hence  they  are 
termed  primitive  or  formative  fasciculi.  The  fibres  of  the 
anterior  pyramids  may  be  traced  upwards  to  the  margin  of 
the  pons,  where  they  become  somewhat  constricted.  From 
the  inner  border  of  each,  fibres  pass  across  the  middle 
sulcus,  and  mutually  change  place,  or  decussate,  those  of 
the  right  side  passing  to  the  left  and  vice  versa.  If  an  in- 
cision, a line  or  two  in  depth,  be  made  through  the  pons, 
so  that  one  lateral  half  of  it  may  be  turned  outwards,  the 
fibres  of  the  pyramid  will  be  observed  to  pass  into  a quan- 
tity of  gray  substance  lodged  in  the  interior  of  the  nodus 
encephali.  In  this  situation  the  fibres  diverge  and  sepa- 
rate, and  are  also  considerably  increased : at  the  upper 
margin  of  the  pons  they  become  continuous  with  the  crus 
cerebri.  Here  an  additional  increase  is  derived  from  their 


NERVOUS  SYSTEM. 


135 


passage  through  the  gray  substance  lodged  in  the  interior 
of  the  crus,  after  which  they  proceed  through  the  inferior 
cerebral  ganglion  (thalamus  nervi  optici),  and  in  the  next 
place  through  the  superior  one  (coipus  striatum),  being 
successively  increased  and  rendered  still  more  divergent, 
until  they  finally  reach  the  anterior  and  middle  lobes,  where 
they  are  evolved  into  their  inferior,  external,  and  anterior 
convolutions.  The  corpus  olivare  contains  within  itself 
a small  ganglion  ; its  fibres  pass,  without  any  decussation, 
into  the  gray  substance  lodged  in  the  cerebral  protuber- 
ance, where,  like  the  pyramids,  they  receive  additions,  after 
which  they  pass  into  the  crus  cerebri,  of  which  they  form 
the  posterior  and  inner  part.  Continuing  their  ascent, 
they  pass  through  the  optic  thalamus,  and  thence  into  the 
corpus  striatum,  receiving  additions  as  they  radiate  through 
each,  and  finally,  are  continued  upwards  into  the  convolu- 
tions at  the  summit  of  the  hemisphere,  and  backwards  into 
those  of  the  posterior  lobe.  Previously  to  entering  the 
optic  thalamus,  some  fibres  of  the  corpus  olivare  have  been 
observed  to  turn  inwards,  so  as  to  give  to  the  tubercula 
quadrigemina  their  medullary  investment,  and  also  to  unite 
with  those  of  the  opposite  side,  to  form  the  valve  of 
Vieussens.  The  diverging  fibres  thus  traced  up  through . 
their  successive  steps  of  increase,  terminate  in  the  gray 
substance  of  the  convolutions ; but  another  order  of  fibres 
may  be  observed  quite  distinct  from  these  and  taking  a 
different  direction.  These  are  called  the  converging  fibres, 
as  they  commence  at  the  peripheral  terminations  of  the 
preceding  set,  and  pass  from  without  inwards  to  the  mid- 
dle line,  so  as  to  connect  the  lateral  parts,  and  bring  them 
into  relation  with  one  another  : on  which  account  they  are 
called  commissures.  The  anterior  and  posterior  commis- 
sures are  formed  in  this  way,  as  is  also  the  corpus  callosum ; 
though  the  greater  number  of  the  fibres  which  compose 
the  latter  are  transverse,  those  towards  its  extremities  are 


136 


NERVOUS  SYSTEM. 


oblique.  This  is  owing  to  the  manner  in  which  the  con- 
verging fibres  of  the  anterior  lobe  are  constrained  to  pass 
from  before  backwards,  and  those  of  the  posterior  lobe 
from  behind  forwards,  in  order  to  gain  the  corresponding 
borders  of  the  corpus  callosum.  By  this  arrangement  a 
greater  number  of  fibres  are  collected  to  its  extremities, 
which  renders  them  thicker  (particularly  the  posterior  one) 
than  any  other  part  of  its  extent.  Some  of  the  inferior 
fibres  thus  traced  from  without  inwards,  instead  of  uniting 
with  the  corresponding  set  along  the  middle  line,  become 
reflected  downwards  from  the  under  surface  of  the  corpus 
callosum  to  the  fornix,  the  fibres  of  which  are  stretched 
from  behind  forwards  in  such  a way,  that  whilst  its  body  is 
in  a manner  unattached,  the  extremities  are  identified  with 
the  parts  just  referred  to. 

The  formative  fibres  of  the  cerebellum  are  derived  from 
the  posterior  pyramids,  or  corpora  restiformia  : they  pass 
upwards  and  outwards,  and  soon  meet  the  corpus  rhom- 
boideum,  which  is  considered  as  the  ganglion  of  the  cere- 
bellum : the  fibres  are  supposed  to  proceed  through  the 
gray  substance  of  which  it  is  composed,  though  it  is  diffi- 
cult to  demonstrate  the  fact ; after  which  they  pass  out- 
wards, diverging  into  the  lobes  of  the  cerebellum.  The 
converging  fibres,  by  their  union,  form  the  crura  cerebelli, 
and  the  fibres  of  the  crus,  expanding  as  they  pass  down- 
wards and  inwards,  constitute  by  their  junction  the  pons 
Varolii,  which  brings  the  lateral  lobes  of  the  cerebellum 
into  relation,  and  forms  their  commissure.  The  processus 
a cerebello  ad  testes  bring  the  lobes  of  the  cerebellum  into 
intimate  connexion  with  the  cerebral  hemispheres. 


ART.  VIII. 


CHAP.  I. 


PARTICULAR  ORGANS  OF  SENSATION. 

THE  EYE  AND  ITS  APPENDAGES. 

The  eye  and  its  appendages  consist  of  the  globe  of  the 
eye,  the  eyebrow,  the  eyelids,  the  ciliie,  the  Meibomian, 
and  the  lachrymal  glands. 


EYEBROWS. 

The  eyebrows  are  covered  with  short  stifi'  hairs,  gene- 
rally of  the  same  color  as  the  hair  of  the  head.  The 
skin  in  which  the  bulbs  of  the  hair  are  implanted,  is 
placed  upon  a thick  layer  of  adipose  cellular  tissue.  The 
frontal,  the  corrugator  supercilii,  and  the  orbicularis  palpe- 
brarum muscles  move  them  in  the  various  expressions  of 
the  face. 

The  projection  of  the  eyebrow  guards  the  eye  against 
external  violence  ; the  hairs,  on  account  of  their  oblique 
direction,  and  the  oily  matter  with  which  they  are  covered, 
prevent  the  perspiration  from  flowing  towards,  or  irritating 

VOL.  II.  IS 


ORGANS  OF  SENSATION. 


lOu 

the  eye  ; they  direct  it  towards  the  temple,  and  the  root  of 
the  nose. 


EYELIDS.  (pALPEBRiE.) 

The  eyelids  are  those  movable  veils  which  cover  the 
anterior  part  of  the  globe  of  the  eye. 

The  upper  eyelid  is  possessed  of  great  mobility  ; it  is 
chiefly  by  it  that  the  eye  is  closed,  for  the  motion  of  the 
lower  eyelid  is  very  limited. 

The  two  eyelids  are  united  at  their  extremities,  forming 
two  angles,  of  which  the  inner  is  more  open  than  the 
outer.  The  edges  of  the  eyelids  are  supported  by  fibro- 
cartilages,  named  the  tarsal  cartilages,  which  keep  the  eye- 
lids always  extended  and  accommodated  to  the  form  of 
the  globe  of  the  eye. 

The  posterior  edges  of  the  cartilages  are  so  shaped  as  to 
form  a triangular  groove  for  the  tears,  when  the  eyelids  are 
shut,  and  as  the  outer  angle  of  the  eyelids  is  higher  than 
the  inner,  the  tears  are  directed  towards  the  puncta  lachry- 
malia,  wliich  are  situated  at  the  inner  angle. 

The  eyelids  cover  the  eye  during  sleep,  and  preserve  it 
from  the  injurious  effects  of  extraneous  particles  flying 
about  in  the  air ; they  defend  it  from  sudden  shocks  by  an 
instantaneous  closure;  and  by  their  repeated  motions 
(nictation)  diffuse  the  lachrymal  fluid  over  the  surface, 
and  preserve  it  in  that  polished  state  which  is  necessary 
for  perfect  vision.  The  eyelids  also  by  their  partial  clo- 
sure, moderate  the  effects  of  too  brilliant  a light,  by  ad- 
mitting only  so  much  as  will  not  offend  the  eye. 

The  eyelashes,  or  cilicE,  are  strong  hairs,  most  commonly 
of  the  same  color  as  the  hair  of  the  head,  and  are  arranged 
in  double  or  triple  rows  on  the  edges  of  the  eyelids  ; those 
of  the  upper  eyelid  are  longer  than  those  of  the  lower,  and 


ORGANS  OF  SENSATION. 


139 


are  curved  upwards  ; those  of  the  under  eyelid  are  direct- 
ed downwards. 

These  hairs  act  as  a shade  to  the  eye,  moderate  the  in- 
tensity of  the  light,  and  prevent  dust  and  other  extraneous 
substances  from  falling  into  the  eye. 

The  Meibomian  glands,  or  ciliary  follicles,  are  small 
glandular  bodies  situated  in  grooves,  between  the  tarsal 
cartilages  and  the  tunica  conjunctiva  ; they  are  arranged  in 
two  vertical  lines ; these  follicles  communicate  with  each 
other,  and  those  nearest  the  edges  of  the  eyelid  open  by 
minute  orifices  behind  the  cilise. 

A sebaceous  matter  exudes  through  the  orifices  of  these 
glands,  and  which  may  be  seen  in  the  form  of  minute 
cylinders,  on  pressing  the  tarsal  cartilages. 

The  tunica  conjunctiva,  or  tunica  adnata,  is  a very  thin 
transparent  mucous  membrane,  which  lines  the  posterior 
surface  of  the  eyelids,  and  is  continued  over  the  fore  part 
of  the  globe  of  the  eye.  It  becomes  thin  and  transpa- 
rent on  the  cornea,  so  much  so,  that  some  anatomists 
have  doubted  whether  it  extends  over  the  entire  of  its  sur- 
face. 

On  the  inner  angle  of  the  eye  the  tunica  conjunctiva 
forms  a small  crescent-shaped  fold,  which  has  some  resemb- 
lance to  the  third  eyelid  of  birds,  and  is  therefore  named  by 
some  anatomists  the  memhrana  nictitans.* 

The  caruncula  lachryrnalis,  is  a small  membranous  ele- 
vation situated  in  the  inner  angle  of  the  eye  ; it  is  formed 
by  a fold  of  the  tunica  conjunctiva,  in  the  substance  of 
which  are  mucous  follicles,  and  the  bulbs  of  some  very 
minute  hairs. 

The  rose  color  of  this  small  body  indicates  the  energy  of 

* This  loose  fold  of  the  conjunctiva  has  not  the  office  nor  the  muscular 
apparatus  of  the  nictitating  membrane,  and  is  consequently  very  erroneously 
named. 


140 


ORGANS  OF  SENSATION. 


the  general  system,  and  its  paleness,  on  the  contrary,  de- 
notes a state  of  debility  and  sickness.* 


THE  GLOBE  OF  THE  EYE  IN  GENERAL. 

The  eye  is  composed  of  two  distinct  portions  of  a sphere 
united  to  each  other ; the  anterior  segment,  which  forms 
about  the  fifth  part  of  the  globe,  has  the  smallest  diameter. 
See  Fig.  39. 


1.  THE  SCLEROTICA. 

The  sclerotica,  (cornea  opaca)  is  a strong,  opaque, 
fibrous  substance,  which  preserves  the  globular  figure  of 
the  eye  ; it  is  an  envelope  which  defends  its  more  delicate 
internal  structure,  and  serves  as  a point  of  insertion  for 
those  muscles  which  move  the  eye.  It  forms  about  four 
fifths  of  the  external  investment  of  the  eye,  extending  from 
the  entrance  of  the  optic  nerve  to  the  border  of  the  cornea. 
The  external  surface  is  in  relation  with  the  conjunctiva,  the 
expansions  of  the  muscles,  and  the  vessels  and  nerves  of 
the  orbit.  It  has  on  its  internal  face  the  choroid  membrane. 
Posteriorly  it  is  pierced  by  the  optic  nerve,  and  this  aper- 
ture is  divided  by  a number  of  septa,  so  as  to  constitute  a 
cribriform  plate  through  which  the  pulp  of  the  nerve  passes. 
Anteriorly  it  receives  the  cornea  which  is  inserted  into  it 
somewhat  like  a watch-glass  into  its  case. 

2.  THE  CORNEA. 

The  cornea  ( cornea  pellucida)  forms  the  anterior  trans- 

*A  description  of  the  lachrymal  apparatus  is  given  in  the  article  on  tlie 
organs  of  secretion. 


ORGANS  OF  SENSATION. 


141 


parent  portion  of  the  globe  of  the  eye ; it  is  not  perfectly 
circular,  the  transverse  diameter  being  a little  longer  than 
the  vertical.  The  cornea  is  encased  in  an  aperture  of  the 
sclerotica,  and  presents  the  appearance  of  a segment  of  a 
small  sphere  added  to  a larger.  Its  anterior  surface,  which 
is  convex,  is  in  contact  with  the  conjunctiva  ; the  posterior 
is  concave,  and  is  lined  by  the  membrane  of  the  aqueous 
humor.  Its  degree  of  convexity  varies  in  different  indi- 
viduals, and  at  the  different  periods  of  life. 

The  cornea  is  thicker  than  the  sclerotica,  and  is  com- 
posed of  several  distinct  laminae  superimposed  on  each 
other  ; it  does_  not  appear  to  contain  either  blood-vessels  or 
nerves.  When  the  eye  is  removed  from  its  socket,  and 
compressed  between  the  fingers,  a serous  fluid  exudes  from 
between  the  laminae  of  the  cornea. 

Part  of  the  light  which  reaches  the  cornea  is  reflected 
from  its  finely  polished  surface,  and  thus  contributes  to  the 
brilliancy  of  the  eye  ; but  its  principal  office  is  to  cause  the 
rays  to  converge  to  the  axis  of  the  eye. 


THE  CHOROID  MEMBRANE. 

The  choroid,  or  the  second  membrane,  is  of  a dark  brown 
color,  soft,  cellular,  and  vascular ; it  is  situated  on  the 
inner  surface  of  the  sclerotica  ; its  outer  surface  is  con- 
nected to  the  sclerotica  by  vessels  and  nerves  ; its  inner 
surface  is  merely  contiguous  to  the  retina  without  adhering 
to  it. 

The  choroid  membrane  is  chiefly  composed  of  minute 
arteries*  and  veins,  united  by  fine  cellular  tissue  ; it  is  so 

* The  ciliary  arteries  are  described  in  Vol.  I.  p.  370.  The  veins  have  a 
peculiar  arrangement,  being  disposed  in  whirls,  and  are  therefore  denomina- 
ted vasa  vorticosa,  and  open  into  the  ophthalmic  vein. 


U2 


ORGANS  OF  SENSATION. 


e.x'ceedingly  vascular,  that  after  a successful  injection  of 
its  blood  vessels,  it  assumes  a uniform  red  color.  These 
vessels  form  two  laminae,  which  may  be  separated  from 
each  other.  The  inner  lamina  was  first  successively  in- 
jected by  Ruysch,  and  his  son  subsequently  named  it 
tunica  Ruyschiana. 

The  pigmentiim  nigrum  is  a dark  brown  substance,  cov- 
ering the  outer  and  inner  surface  of  the  choroid  mem- 
brane ; on  the  latter  surface  this  substance  is  more  abun- 
dant, and  is  in  immediate  contact  with  the  retina.  Its 
office  is,  apparently,  to  absorb  the  rays  of  light  immedi- 
ately after  they  have  impinged  on  the  sensible  surface  of 
the  retina.* 

Persons  termed  Albinoes  have  no  pigmentum  nigrum, 
therefore  the  iris  and  pupil  appear  of  a red  color,  and  their 
vision  is  very  imperfect,  that  is,  they  cannot  view  objects 
in  a strong  light ; even  during  the  day  time  they  can 
scarcely  see  sufficiently  to  go  about. 

THE  CILIARY  CIRCLE  OR  LIGAMENT. 

Towards  the  margin  of  the  cornea,  the  choroid  adheres 
firmly  to  the  sclerotica,  constituting  what  is  termed  the  lig- 
amentum  ciliare ; within,  it  has  the  appearance  of  folds, 
which  are  called  the  ciliary  processes ; they  indent  the  hya- 

*MrG.  H.  Fielding,  in  a communication  delivered  at  Oxford,  before  a 
meeting  of  the  British  Association,  stated  his  opinion,  that  this  substance 
does  not  at  all  possess  the  properties  of  a pigment;  that  its  colors  are  not, 
as  it  has  been  supposed  to  be,  the  result  of  any  secreted  matter;  that  it 
consists  of  layers  separable  from  the  Ruyschiana:  that  it  possesses  elasticity, 
and  above  all,  circulation ; he  thinks,  therefore,  that  we  are  warranted  in 
coming  to  the  conclusion,  that  it  is  a membrane,  and  not  a pigment. 

To  this  membrane  he  has  given  the  name  of  membrana  versicolor, 
from  the  great  variety  of  color  it  has  in  different  animals.  He  supposes 
that  it  receives  the  impression  of  images  through  the  transparent  retina. 


ORGANS  OF  SENSATION. 


143 


loid  membrane,  where  it  splits  to  form  the  Petitian  canal. 
The  intervals  of  these  processes  are  covered  by  the  pigmen- 
tum  nigrum. 

These  ciliary  processes  are  sixty  or  seventy  in  number, 
arranged  in  a radiated  manner  around  the  lens,  on  the  fore- 
part of  the  vitreous  humour.  Each  extends  inwards  and 
backwards  from  the  ciliary  ligament  as  far  as  the  border  of 
the  lens.  The  anterior  edge  of  each  process  is  connected 
to  the  ciliary  ligament  and  iris,  the  posterior  to  the  vitre- 
ous humour  ; and  the  internal  is  loose,  and  forms  the  cir- 
cumference of  the  posterior  chamber  of  the  eye. 

THE  IRIS. 

The  iris  is  a delicate  circular  membrane,  floating  in  the 
aqueous  humour,  and  suspended  vertically  behind  the  cor- 
nea, so  as  to  divide  the  space  between  this  and  the  lens 
into  two  chambers,  an  anterior  and  posterior ; the  former 
is  the  larger  of  the  two.  These  chambers  communicate 
through  the  central  aperture  in  the  iris,  the  pupil. 

The  iris  is  so  named  from  its  being  of  different  colors  ;* 
it  is  a kind  of  circular  curtain  placed  in  the  anterior  part 
of  the  eye,  to  regulate  the  quantity  of  light  passing  to  the 
back  part  of  the  eye. 

The  outer  circumference  is  attached  to  the  ciliary  circle  ; 
its  inner  circumference  forms  the  limits  of  the  pupil. 

The  iris  floats  in  the  aqueous  humour,  and  is  of  a very 
contractile  nature,  so  that  when  the  eye  is  exposed  to  a 
strong  light,  or  when  we  look  upon  a near  object,  the 
diameter  of  the  pupil  is  diminished  ; and  vice  versa. 

Upon  the  back  part  of  the  iris  there  is  a dark  colored 

* The  color  of  the  iris  in  general  corresponds  with  that  of  the  hair,  being 
blue  or  gray  where  the  hair  is  light,  and  browner  black  where  the  hair  and 
complexion  are  of  a dark  color. 


144 


ORGANS  OF  SENSATION. 


secretion,  resembling  the  pigmentum  nigrum.  This  sur- 
face is  called  the  uvea. 

The  iris  is  composed  of  two  laminas,  intimately  united 
near  the  pupil.  Some  anatomists  of  great  merit  state  that 
these  laminae  are  two  sets  of  muscular  fibres,  the  one  con- 
centric, round  the  pupil,  composed  of  circular  fibres  con- 
tracting the  pupil  in  the  manner  of  a sphincter;  the 
other  radiated,  and  having  by  its  muscular  action  the 
power  of  contracting  the  iris,  and  consequently  enlarging 
the  pupil. 

The  ciliary  arteries,  which  supply  the  opposite  sides  of 
the  iris,  freely  unite  with  each  other  ; and  the  smaller  ves- 
sels of  the  iris  form  a circle  round  the  pupil. 

The  iris  is  supplied  with  nerves  by  filaments  from  the 
ciliary  nerves. 

The  motions  of  the  iris  are  involuntary,  and  depend  on 
the  quantity  of  light  falling  on  the  retina;  for  when  the 
retina  loses  its  sensibility,  the  iris  does  not  move,  but  re- 
mains dilated. 

The  pupil  in  the  foetus  is  closed  by  a delicate  but  vascu- 
lar membrane,  termed  the  membrana  pupillaris,  which  is 
either  ruptured  at,  or  a short  time  previous  to  birth. 

THE  RETINA. 

The  retina  (tunica  nervea)  is  called  the  third  membrane 
of  the  eye  ; it  is  a soft,  thin,  semitransparent,  nervous 
expansion,  extending  from  the  optic  nerve  to  the  crys- 
talline lens,  embracing  the  vitreous  body,  and  lining  the 
choroid  membrane  without  adhering  to  either  of  these  two 
parts. 

At  the  posterior  part  of  the  retina,  and  exactly  in  the 
axis  of  vision,  there  is  a circular  foramen  surrounded  by 
a bright  yellow  border.  This  was  discovered  by  Soem- 


ORGANS  OF  SENSATION. 


145 


MERiNG,  and  is  named  the  foramen  centrah,  or  more  fre- 
quently the  foramen  of  Soemmering  ; it  is  about  one 
thirtythird  of  an  inch  in  diameter,  but  its  office  is  not  per- 
fectly understood.  Blumenbach  supposed  that  it  might 
serve  as  a kind  of  pupil,  through  which  concentric  rays 
might  be  absorbed  by  the  choroid,  when  the  eye  was  in 
danger  by  a very  strong  light. 

The  retina  is  divisible  into  three  layers  ; viz.  serous, 
nervous  and  vascular.  The  external  or  serous  is  extremely 
delicate  and  is  the  one  discovered  by  Dr  Jacob,  and  is 
now  known  as  Jacob's  merabrane. 

The  retina  is  the  seat  of  vision,  therefore  the  primary 
part  of  the  eye,  to  which  all  the  other  parts,  within  the 
orbit,  are  subservient ; nevertheless,  that  part  of  the  retina 
which  lies  over  the  entrance  of  the  optic  nerve  is  insensi- 
ble to  light. 

For  the  perfect  functions  of  the  retina,  it  requires  the 
light  within  a certain  degree  of  intensity  : a very  feeble 
light  is  not  felt  by  the  retina ; too  strong  a light  hurts  it, 
and  renders  it  for  some  time  unfit  for  action. 


VOL.  II. 


19 


146 


ORGANS  OF  SENSATION. 


Fig.  39. 


O/ 


Fig.  39.  A diagram  of  the  eye. 
a,  the  eyelid. 

}),  the  tunica  conjunctiva  lining  the  eyelids,  and  reflected 
over  the  anterior  part  of  the  eye. 

c,  c,  the  cornea.  d,  the  sclerotica, 

e,  the  aqueous  humour.  f,  the  iris, 
g-,  the  crystalline  lens.  /i,  the  vitreous  humour, 
i,  the  choroid  tunic  with  its  pigmentum  nigrum. 

T<,  the  ciliary  processes.  I,  the  retina. 

m,  the  punctum  lachrymale. 

n,  the  caruncula  lachrymalis. 

0,  the  central  artery  of  the  retina. 
p,  the  optic  nerve. 


THE  AQ,UEOUS  HUMOUR. 

The  aqueous  humour  is  as  clear  as  the  purest  water,  but 
its  specific  gravity  is  somewhat  greater ; it  is  about  five 


ORGANS  OF  SENSATION. 


147 


^rains  in  weight,  and  consists  of  water  impregnated  with 
albumen,  gelatin,  and  muriate  of  soda. 

The  aqueous  humour  is  situated  between  the  cornea  and 
crystalline  lens,  and,  being  confined  in  this  space,  forms  a 
meniscus,  which  assists  in  collecting  and  transmitting  the 
rays  of  light  to  the  inner  part  of  the  eye. 

The  light  only  which  passes  the  pupil  can  be  of  use  in 
vision  ; that  which  falls  on  the  iris  is  reflected,  returns 
through  the  cornea,  and  exhibits  the  color  of  the  iris. 

The  membrane  of  the  aqueous  humour  is  extremely  thin, 
and  perfectly  transparent,  lining  all  the  anterior  chamber 
of  the  eye,  but  not  extending  to  the  posterior  chamber. 
The  first  of  these  chambers  is  about  two  lines,  the  latter 
about  half  a line  in  depth.  This  membrane  secretes  the 
aqueous  humour  in  the  first  instance,  and  reproduces  it 
when  evacuated  by  accident  or  during  operations. 


THE  CRYSTALLINE  LENS. 

The  crystalline  lens  is  a transparent  body  placed  be- 
tween the  aqueous  humour  and  the  vitreous  body,  lying 
behind  the  iris,  surrounded  by  the  ciliary  processes.  It  is 
a double  convex  lens,  of  which  the  anterior  surface  is  flat- 
ter than  the  posterior,  the  diameter  of  which  is  four  lines, 
and  its  thickness  about  two ; its  axis  corresponds  to  the 
centre  of  the  pupil. 

The  lens  appears  to  be  composed  of  several  disti....t 
layers,  an  exterior,  very  soft  and  easily  removed,  and  the 
interior  forming  a more  solid  nucleus,  made  up  of  a great 
number  of  concentric  superimposed  lamin®  ; and  each  of 
these  laminae  is  composed  of  very  fine  fibres,  like  those  of 
spun  glass. 

If  the  lens  be  dried  it  may  also  be  divided  into  three 
segments  of  a sphere,  in  the  centre  of  which  there  exists  a 
small  transparent  globule. 


148 


ORGANS  OF  SENSATION. 


In  its  chemical  composition  it  differs  very  little  from  the 
aqueous  humour,  only  in  having  a larger  proportion  of 
gelatin  and  albumen,  and  in  being  free  from  saline  matters. 

The  membrane,  or  capsule,  of  the  lens  is  also  perfectly 
pellucid,  and  adheres  very  slightly  to  the  lens,  so  that  when 
the  capsule  is  punctured,  upon  making  gentle  pressure  on 
the  eye,  the  lens  starts  out.  The  capsule  receives  a mi- 
nute branch  of  the  central  artery  of  the  retina,  and  ramifi- 
cations of  the  vessels  of  the  ciliary  processes.  It  encloses 
a small  quantity  of  fluid  which  is  termed  liquor  Morgagni. 

The  crystalline  lens  is  retained  in  its  situation  by  nu- 
merous delicate  transparent  filaments,  which  pass  from  the 
ciliary  processes  to  the  circumference  of  the  capsule  of  the 
lens. 

The  office  of  the  lens  is  not  only  to  assemble  the  rays 
of  light  upon  a certain  part  of  the  retina,  but  to  increase 
the  intensity  of  the  light,  which  is  directed  towards  the 
back  of  the  eye.  It  may  also  be  added,  that  the  light 
which  passes  near  the  circumference  of  the  crystalline 
lens,  is  probably  refracted  in  a different  manner  from  that 
which  passes  through  the  centre  ; so  that  its  peculiar 
structure  is  supposed  to  have  the  effect  of  correcting  that 
aberration  which  is  always  produced  by  the  sphericity  of 
ordinary  lenses. 


THE  VITREOUS  BODY. 

The  vitreous  body,  or  humour,  is  so  called  from  its  re- 
semblance to  melted  glass : it  is  a perfectly  transparent 
tremulous  mass,  occupying  the  globe  of  the  eye,  from  the 
entrance  of  the  optic  nerve  to  the  surface  of  the  crystal- 
line lens,  or  about  the  posterior  two-thirds  of  the  globe. 
It  is  invested,  in  nearly  its  whole  extent,  by  the  retina,  but 
to  which  it  is  not  adherent ; so  that  its  connection  with  the 


ORGANS  OF  SENSATION. 


149 


Other  parts  of  the  eye,  is  merely  by  the  central  artery  of 
the  optic  nerve,  which  passes  through  it,  to  the  posterior 
part  of  the  capsule  of  the  lens. 

The  vitreous  body  is  composed  of  a fluid  or  humour 
contained  in  cells,  formed  of  the  hyaloid  membrane. 

Tlie  chemical  properties  of  the  fluid  of  the  vitreous  body 
are  similar  to  those  of, the  aqueous  humour. 

The  hyaloid  membrane,  which  contains  the  vitreous  hu- 
mour, is  excessively  thin  and  transparent,  and  constitutes 
an  innumerable  mass  of  cellules  which  communicate  with 
each  other,  so  that  by  making  a puncture  in  the  hyaloid 
membrane  the  whole  humour  will  escape. 

Fig.  40,  the  refracting  media  of 
the  eye. 

a,  the  aqueous  humour. 
h,  the  crystalline  lens. 
c,  the  vitreous  humour. 

The  Petition  canal  is  named  after 
Petit,  who  discovered  it.  This  ca- 
nal, Fig.  41,  is  formed  merely  by,  b, 
vitreous  humour  which  passes  before 
lens,  and  becomes  identified  with  its 
capsule ; thus,  leaving  at,  c,  its  mar- 
gin, a somewhat  triangular  space, 
which  may  be  demonstrated  by  infla- 
tion : although,  strictly  speaking,  it 
does  not  exist  in  its  natural  state,  for 
the  laminae  are  in  perfect  contact,  the  canal  being  formed 
artificially,  by  blowing  air  between  the  posterior  surface  of 
the  capsule  of  the  lens,  and  the  hyaloid  membrane  on 
which  the  lens  rests. 

The  anterior  lamina  of  the  canal  of  Petit  presents  ra- 
diated striae  and  contractions,  corresponding  to  the  ciliary 
process,  forming  a curious  and  beautiful  appearance. 

The  vitreous  body  possesses  a less  refractive  power  than 


Fig.  40. 


the  laminae  of  the 
and  behind,  a,  the 


Fig.  41. 


150 


ORGANS  OF  SENSATION. 


the  crystalline,  therefore,  after  the  rays  are  collected  by 
the  latter,  the  vitreous  body  continues  their  convergence, 
increases  the  field  of  vision,  and  assists  in  bringing  the 
rays  to  an  accurate  focus  on  the  retina. 


CHAP.  II. 

THE  EAR  AND  ITS  APPENDAGES. 

There  are  a number  of  organs  in  the  apparatus  of  hear- 
ing, which,  by  their  physical  properties  and  functions,  con- 
cur in  collecting  and  transmitting  sounds,  and  there  is  a 
nerve  for  the  purpose  of  receiving  and  conveying  the  im- 
pressions of  sonorous  vibrations  to  the  sensorium. 

The  organ  of  hearing  is  divisible  into  three  parts,  viz. 
the  external  ear,  or  auricula,  the  tympanum,  and  the  laby- 
rinth. 


THE  EXTERNAL  EAR. 

The  external  ear  comprehends  the  pinna  or  auricle,  and 
the  meatus  auditorius  externus. 

The  auricle  consists  of  the  pavilion  or  ala,  which  is  by 
much  the  greater  part  of  it,  and  the  lobus  which  is  the  most 
dependent  portion. 

The  exterior  of  the  ear  presents  the  following  remark- 
able prominences  and  depressions,  viz:  — 


ORGANS  OF  SENSATION. 


151 


Fig.  42. 


1.  h,h,  Fig.  42,  the  helix,  a rim  of 
nearly  a semicircular  shape  surround- 
ing its  upper  edge  ; and  continued 
to,  I,  the  lobe  of  the  ear. 


2.  a,  the  anti-helix,  an  inner  semi- 
circular eminence,  which  is  situated 
within  the  former,  and  is  formed  su- 
periorly of  two  ridges  uniting  to- 
gether below  — 


s,  the  scapha,  the  depression  which 


separates  the  two  roots  of  the  anti-helix. 

3.  t,  the  tragus,  a small  eminence  situated  over  the 
meatus  externus,  and  connected  to  the  under  and  fore  part 
of  the  helix. 

4.  a,  t,  the  anti-tragus,  is  another  eminence  situated 
behind,  nearly  opposite  to  the  tragus,  and  at  the  inferior 
extremity  of  the  anti-helix. 

5.  c,  the  concha,  is  a large  cavity  under  the  anti-helix, 
and  leading  to  the  meatus  auditorius. 

6.  I,  the  lohe  of  the  ear,  is  the  inferior  soft  part  of  the 
ear,  and  is  composed  of  cellular  tissue  with  a small  quan- 
tity of  fat.  This  is  the  part  which  it  has  been  customary, 
in  many  countries,  to  perforate  for  the  purpose  of  suspend- 
ing rings  and  other  ornaments. 

The  office  of  the  auricle  of  the  external  ear  is  to  collect 
the  sonorous  radiations,  and  to  direct  them  towards  the 
auditory  passage. 


152 


ORGANS  OF  SENSATION. 


FIBRO-CARTILAGE  OF  THE  EAR. 


The  fibro-cartilage  of  the  ear, 

Fig.  43,  constitutes  its  basis,  deter- 
mining the  form  of  that  part : in  its 
consistence  and  elasticity,  it  is  analo- 
gous to  those  of  the  nose. 

All  the  eminences  and  depres- 
sions just  described  are  formed  by 
it,  as  may  be  seen  in  the  annexed 
figure  — A,  A,  the  cartilage  of  the 
helix ; a,  the  anti-helix  ; s,  the  sca- 
pha ; t,  the  tragus ; a,  t,  the  anti-tragus  ; c,  the  concha. 
These  fibro-cartilages  are  covered  by  a dermal  layer,  having 
a great  number  of  sebaceous  follicles  disposed  through 
it.  The  inner  surface  of,  t,  the  tragus  is  furnished  with 
hairs,  which  appear  destined  to  prevent  small  particles, 
which  float  in  the  atmosphere,  from  entering  the  auditory 
passage. 

There  are  ligaments  which  serve  to  fix  the  fibro-cartilage 
to  the  side  of  the  head,  called  the  superior,  the  anterior, 
and  the  posterior  ligaments ; they  are  more  cellular  than 
fibrous,  and  are  intermingled  with  the  muscular  fibres  of 
the  auricle. 

The  principal  muscles  of  the  ear  have  been  already  de- 
scribed, and  those  that  remain,  which  belong  to  the  carti- 
lage, are  of  small  size  ; one  or  more  of  them  are  sometimes 
absent ; at  other  times,  Cloq,uet  states,  he  could  meet  with 
none  ; indeed,  so  insignificant  are  these  muscles  that  I am 
not  aware  that,  in  any  person,  they  possess  the  power  of 
moving  the  part  they  are  attached  to.  The  following, 
however,  is  an  enumeration  of  them. 

1.  The  transversus  auris,  extending  from  the  convexity 


ORGANS  OF  SENSATION. 


153 


of  the  concha,  to  the  prominence  which  the  groove  of  the 
helix  forms  posteriorly^ 

2.  The  tragicus  is  of  a triangular  form,  and  almost  en- 
tirely covers  the  outer  surface  of  the  tragus. 

3.  The  anti-tragicus  occupies  the  interval  which  sepa- 
rates the  anti-tragus  from  the  anti-helix. 

4.  The  helicis  major  covers,  for  a few  lines,  the  helix 
above  the  tragus. 

5.  The  helicis  minor  is  situated  beneath  and  behind  the 
preceding,  on  the  prominence  of  the  helix. 

I , The  muscles  of  the  external  ear,  no  doubt,  are  calcula- 
ted to  expand  the  different  hollows  of  which  the  surface  is 
formed.  Among  savage  tribes  the  ear  is  prominent  and 
movable,  like  the  ears  of  animals  ; their  hearing  is  more 
acute  than  that  of  civilized  nations  ; and  it  is  probable, 
that  the  motion  of  the  external  ear  assists  them  in  discrim- 
inating the  nature  of  different  sounds. 


THE  AUDITORY  CANAL. 

This  canal  extends  from  the  concha  of  the  ear  to  the 
membrane  of  the  tympanum  ; it  is  composed  of  bone  and 
cartilage,  lined  by  a very  fine  skin,  and  defended  by  a pe- 
culiar acrid  sebaceous  substance,  the  cerumen,  or  the  wax, 
furnished  by  the  cerumenous  glands ; this  canal  is  also 
fenced  by  a number  of  hairs.  It  takes  a direction  first 
forwards,  upwards,  and  inwards,  then  downwards  and  in- 
wards. It  is  therefore  curved,  or  concave  downwards,  and 
about  an  inch  in  length. 


20 


VOL.  II. 


154 


ORGANS  OF  SENSATION. 


THE  INTERNAL  EAR. 

The  internal  ear  consists  of  the  cavity  of  the  tympanum, 
the  vestibule,  the  cochlea,  and  the  parts  communicating 
with  them. 

The  tympanum  is  a narrow  chamber  which  opens  into 
the  posterior  fauces  through  the  Eustachian  tube,  and  is 
continued  backwards  into  the  cells  of  the  mastoid  process 
of  the  temporal  bone. 

The  Eustachian  tube  descends  obliquely  forwards  and 
inwards,  and  terminates  in  a trumpet-shaped  mouth,  be- 
hind the  posterior  nares,  on  a level  with  the  inferior  spongy 
bone.  It  is  small  and  osseous  posteriorly ; anteriorly  it  is 
large,  and  formed  externally  of  membrane,  and  internally 
of  fibro-cartilage.  It  is  lined  by  mucous  membrane. 
Through  this  tube,  the  air  can  pass  from  the  fauces  into 
the  tympanum,  to  support  the  latter  on  its  internal  sur- 
face. 

The  membrana  tympani  is  extended  over  the  circular 
opening,  at  the  bottom  of  the  external  meatus. 

The  foramen  ovale,  or  fenestra  ovalis,  is  an  aperture  of  a 
shape  which  the  name  implies  ; it  forms  a communication 
between  the  tympanum  and  vestibule. 

The  foramen  rotundum,  or  fenestra  rotunda,  is  of  smaller 
dimensions  than  the  preceding  foramen,  and  forms  a com- 
munication between  the  inner  scala  of  the  cochlea  and  the 
tympanum. 

The  promontorium  is  an  eminence  formed  by  the  outer 
side  of  the  vestibule,  and  by  the  corresponding  scala  of  the 
cochlea. 


ORGANS  OF  SENSATION. 


155 


THE  BONES  CONTAINED  IN  THE  CAVITY  OF  THE  TYMPA- 
NUM, OR  THE  OSSICULA  AUDITUS. 


A series  of  very  small  bones*  extends  from  the  mem- 
brana  tympani  to  the  fenestra  ovalis  and  consequently  to 
the  labyrinth.  These  convey  to  the  deepest  parts  of  the 
internal  ear,  the  changes  which  supervene  in  the  membrane 
of  the  tympanum.  They  are  named  the  malleus,  the  incus, 
the  os  orhiculare,  and  the  stages,  and  there  are  muscles  ap- 
propriated to  put  them  into  motion. 

The  malleus,  Fig.  44,  which  is  described 
as  having  a head,  a neck,  a handle,  and  a 
process. 

The  handle  of  the  malleus  is  attached 
to  the  membrana  tympani,  being  situated 
between  the  layers  of  it. 


Fig.  45. 


The  incus.  Fig.  45,  consists  of  a body 
and  two  crura.  It  is  articulated  to  the 
malleus,  and  is  fixed  by  a ligament  to 
the  sides  of  the  mastoid  cells. 


Fig.  46.  The  os  orhiculare.  Fig.  46,  is  articulated 

® to  the  long  process  of  the  incus. 

Fig.  47.  The  stapes.  Fig.  47,  is  distinguished 

into  a head,  crura,  and  base.  This  bone 
is  placed  horizontally,  with  its  base  resting 
against  the  fenestra  ovalis,  and  its  head 
articulated  with  the  os  orhiculare. 

There  are  three  muscles  by  which  this  series  of  bones  is 
moved : — 

* Tlie  annexed  figures  of  the  bones,  as  well  as  those  which  follow  with 
the  muscles  attached  to  them,  are  magnified  to  twice  the  natural  size. 


15(3 


ORGANS  OF  SENSATION. 


1.  The  laxator  tympani,  Fig.  48,  a,  is 
attached  to  the  upper  part  of  the  edge  of 
the  tympanum,  near  to  the  part  to  which 
the  membrane  of  the  tympanum  adheres, 
and  is  extended  to  the  handle  of  the  mal- 
leus. 

2.  The  tensor  tympani,  c,  is  attached  to 
the  upper  part  of  the  Eustachian  tube,  and  to  the  handle 
of  the  malleus  below  its  process. 

3.  The  extensor  mallei,  h,  or  the  musculus  processus  mi- 
noris  of  Valsalva,  is  figured  by  Sir  C.  Bell,  but  it  is  not 
acknowledged  by  Cloruet  and  some  other  anatomists  to 
be  of  the  nature  of  a muscle. 

4.  The  stapedius.  Fig.  49,  a,  is  the 
smallest  muscle,  and  is  attached  near  the 
mastoid  cells,  and  into  the  head  of,  b,  the 
stapes. 


Fig.  49. 


Fig  48. 


THE  LABYRINTJI.  Fig.  50.* 


* To  obtain  tlie  exact  form  of  the  exterior  of  these  parts,  we  may  pour 
melted  lead  into  the  external  meatus  of  the  temporal  bone,  the  bone  may 
be  afterwards  easily  removed,  and  we  have  a metallic  cast  of  these  delicate 
parts. 


ORGANS  OF  SENSATION. 


157 


The  labyrinth,  so  called  from  its  sinuosities  and  wind- 
ings, is  situated  between  the  tympanum  and  the  meatus 
auditorius  internus  ; it  is  formed  of  several  cavities,  which 
are  designated  by  the  names  of,  a,  the  vestibule,  b,  the 
cochlea,  and,  c,  c,  c,  the  semicircular  canals. 

The  vestibule,  named  from  its  forming  an  entry  to  the 
cochlea  and  semicircular  canals,  is  a cavity  of  an  irregular 
form,  containing  several  apertures,  which  communicate 
with  the  neighboring  parts,  which  we  must  again  notice, 
viz  : — 

1st.  d,  the  fenestra  ovalis,  ox  foramen  ovale,  which  com- 
municates with  the  tympanum,  and  upon  which  is  placed 
the  base  of  the  stapes.  2d.  Superiorly,  the  two  anterior 
orifices  of  the  superior  vertical  and  horizontal  semicircular 
canals.  3d.  Posteriorly,  the  two  separate  openings  of  the 
semicircular  canals,  and  one  opening  common  to  the  two 
vertical  canals.  4th.  On  the  inner  side  is  a number  of 
small  perforations  for  the  transmission  of  blood-vessels  and 
branches  of  the  auditory  nerve.  5th.  Near  the  common 
orifice  of  the  vertical  canals  we  find  the  opening  of  the 
aqueduct  of  the  vestibulum,  extremely  small,  extending 
from  this  cavity  to  the  posterior  surface  of  the  petrous 
portion  of  the  temporal  bone.  i 


THE  COCHLEA. 

The  cochlea.  Fig.  51,  is  situated  on  the  inner  side  of  the 
vestibulum,  in  the  anterior  part  of  the  petrous  portion  of 
the  temporal  bone  ; it  is  an  osseous,  shell-like  cavity,  form- 
ed by  two  conical  canals,  twisted  in  a spiral  direction. 
See  Fig.  50,  b. 


158 


ORGANS  OF  SENSATION. 


Fig.  51. 


Fig.  51,  represents  a section  of  that  part  of  the  pe- 
trous portion  of  the  temporal  bone  which  contains  the 
cochlea. 

1st.  h,  b,  the  modiolus,  an  osseous  conical  pillar  in  the 
centre  of  the  cochlea,  terminating  in  a small  cavity,  c,  call- 
ed the  infundibulum. 

2d.  a,  a,  the  lamina  spiralis,  formed  round,  b,  b,  the 
modiolus,  takes  two  turns  and  a lialf,  and  terminates  by  a 
hook  at  c,  in  the  infundibulum. 

3d.  The  spiral  septum,  dividing  the  cavity  of  the  cochlea 
into  two  smaller  ones. 

4th.  The  gyri,  which  are  the  spiral  cavities  formed  by 
the  septum. 

5th.  The  aqueduct,  an  extremely  narrow  passage  open- 
ing, superiorly,  into  the  cavity  of  the  tympanum,  near  the 
foramen  rotundum  ; inferiorly,  in  the  posterior  petrous  por- 
tion of  the  temporal  bone. 


ORGANS  OF  SENSATION. 


159 


THE  SEMICIRCULAR  CANALS. 

The  form  of  the  three  canals,  Fig.  50,  c,  c,  c,  is  indicated 
by  the  name ; they  are  situated  in  the  substance  of  the 
petrous  portion  of  the  temporal  bone,  and  open  into  the 
vestibulum  by  five  orifices. 

The  cavities  of  the  internal  ear  are  lined  by  a very  deli- 
cate membrane ; and  each  of  the  semicircular  canals  con- 
tains a membranous  tube,  opening  into  a common  sac, 
which  occupies  a portion  of,  (/,  the  vestibulum,  and  con- 
tains a small  quantity  of  a peculiar  fluid.  The  vestibulum 
also  is  lined  by  another  membranous  sac,  filled  with  a 
limpid  fluid,  called  the  liquor  of  Cotunnius  ; it  sends  a 
prolongation  of  its  membrane  into  the  aqueduct  of  the 
vestibulum,  and  this  prolongation  terminates  in  a small 
cul-de-sac  under  the  dura  mater. 

The  membrane  of  the  vestibule  appears  to  introduce 
itself  into  the  cochlea  by  the  orifice  of  the  external  scala, 
lines  all  its  cavities,  is  continued  into  the  aqueduct  of  the 
cochlea,  and  terminates  by  a cul-de-sac  under  the  dura 
mater. 


THE  ACOUSTIC,  OR  AUDITORY  NERVE. 

The  acoustic  nerve  proceeds  parallel  to  the  facial,  so 
long  as  it  is  contained  within  the  skull;  it  then  introduces 
itself  with  it  into  the  internal  auditory  canal,  and  divides 
into  two  branches : — 


160 


ORGANS  OF  SENSATION. 


Fig.  52. 


1.  The  hranch  of  the  cochlea,  Fig.  52,*  a,  on  arriving  at 
the  base  of  the  cochlea,  divides  into  a great  number  of  very 
slender  filaments,  which  enter  into  apertures  of  the  cochlea, 
and  spread  out  their  ramifications  on,  b,  b,  the  lamina  spi- 
ralis in  a very  dense  net-work. 

2.  The  branch  of  the  vestibule  and  semicircular  canals, 
c,  d,  g,  is  at  first  united  to  the  preceding,  but  afterwards 
separates  from  it,  and  forms  an  enlargement,  from  which 
proceed  filaments  which  are  distributed  to,f  the  vestibule, 
and  to,  h,  h,  h,  the  semicircular  canals.  At  the  entrance 
of  the  posterior  vertical  canal,  we  observe,  at  g,  the  in- 
creased size  of  the  nerve  in  the  ampulla,  or  enlargement  of 
the  extremities  of  the  canals. 


MF.CHANISM  OP  HEARING. 

The  external  ear  collects  the  sonorous  radiations,  and 
directs  them  towards  the  auditory  passage  ; and  this  tube 
transmits  sound  in  the  same  manner  as  any  other  canal, 
partly  by  the  air  it  contains,  and  partly  by  its  parietes, 

* Tlie  ihrc'c  last  iigures  are  considerably  enlarged  views. 


ORGANS  OF  SENSATION. 


161 


until  it  arrives  at  the  membrane  of  the  tympanum ; this 
membrane  vibrates  under  the  influence  of  the  sonorous 
undulations  which  the  meatus  conducts  to  it.  The  series 
of  little  bones,  next,  has  a peculiar  action  upon  the  mem- 
brane of  the  fenestra  ovalis,  so  that  the  liquor  of  Cotun- 
Nius  receives  vibrations  which  are  impressed  on  the 
acoustic  nerve. 

The  gyri  of  the  cochlea  receive  the  vibrations  princi- 
pally by  the  membranes  of  the  fenestra  ovalis  ; the  vesti- 
bule, by  the  series  of  bones : the  semicircular  canals,  by 
the  sides  of  the  tympanum  : but  the  assistance  which  is 
given  to  hearing  by  the  several  parts  of  the  internal  ear  is 
totally  unknown. 

It  is,  however,  certain  that  impressions  are  received  and 
transmitted  to  the  brain  by  the  auditory  nerve ; and  the 
brain  perceives  them  with  more  or  less  facility  and  exact- 
ness in  different  individuals. 


VOL.  II. 


21 


162 


ORGANS  OF  SENSATION. 


Fig.  53. 


Fig.  53,  exhibits  the  organ  of  hearing,  of  the  natural 
size. 

a,  the  external  ear. 

b,  the  tympanum,  exposed  by  opening  the  vestibule. 

c,  the  cochlea. 

d,  the  three  semicircular  canals  laid  open. 

e,  the  osseous  part  of  the  Eustachian  tube. 

f,  the  membranous  extremity  of  the  Eustachian  tube, 
opening  into  the  fauces. 

g,  the  petrous  portion  of  the  temporal  bone. 

h,  the  meatus  auditorius  externus,  on  which  is  seen  the 
cerumenous  glands. 

1,  the  stapes  ; 2,  the  os  orbiculare  ; 3,  the  incus  ; 4,  the 
malleus ; a series  of  bones  which  transmits  the  vibrations 
of  the  tympanum. 


ORGANS  OF  SENSATION. 


163 


CHAP.  III. 


THE  NOSE,  OR  ORGAN  OF  SMELL. 


Fig.  54. 


The  external  part  of  the  organ  of  smelling,  or  the  nose, 
properly  so  called,  is  composed  superiorly  of  bones,  and 
inferiorly  of  cartilages ; it  has  a partial  covering  from 
muscles,  and  a general  one  from  the  common  integu- 
ments. 

The  osseous  part  of  the  nose  has 
already  been  described  ; the  ossa  nasi. 
Fig.  54,  a,  forms  the  bridge. 

The  fore  part  of  the  nose  contains 
five  cartilages,  of  a regular  figure,  and 
some  smaller  pieces  which  are  more  ir- 
regular. 

The  middle  cartilage,  c,  is  the  most 
considerable,  and  supports  the  rest;  it 
constitutes  the  cartilaginous  part  of  the 
septum  narium,  and  is  united  to  the  anterior  edge  of  the 
nasal  lamella  of  the  ethmoid  bone,  to  the  anterior  edge  of 
the  vomer,  and  to  the  fore  part  of  the  spinous  process  of 
the  superior  maxillary  bones. 

h,  the  two  superior  lateral  cartilages  are  placed  some- 
what anteriorly,  so  that  by  their  union  they  form  the  centre 
of  the  nose  ; d,  the  two  inferior,  laterally  and  at  the 
extremity,  so  as  to  form  the  tip  of  the  nose ; and,  e,  the 
alae  nasi. 

Between  the  anterior  and  posterior  cartilages  we  find 
additional  cartilages,  the  number,  size,  and  figure,  varying 
in  different  individuals. 


164 


ORGANS  OF  SENSATION. 


The  elasticity  of  the  cartilages  contributes  to  the  defence 
of  the  nose  against  e.vternal  injuries. 

The  muscles  which  move  the  cartilages  of  the  nose  have 
been  described. 

The  internal  cavities  of  the  nose  extend  upwards  to  the 
cribriform  plate  of  the  ethmoid,  and  to  the  body  of  the 
sphenoid  bone.  At  the  inner  side,  they  are  bounded  by 
the  septum  narium,  and  on  the  outer  side,  by  the  turbina- 
ted bones,  which,  as  we  have  seen  in  the  skeleton,  project 
considerably  into  the  nasal  cavities,  and  increase  the  sur- 
face of  the  membrane  of  the  organ  of  smell. 

The  floor  of  the  nostrils  passes  directly  backwards  in  a 
horizontal  direction  to  the  throat. 

The  nose  is  lined  by  a thick  and  spongy  mucous  mem- 
brane, termed,  the  menibrana  pituitaria  of  Schneider,  or 
the  Schneiderian  membrane ; which  secretes  a mucus  that 
defends  the  nerves  from  the  current  of  air  which  is  respired; 
by  this  mean  they  are  preserved  moist,  and  rendered  fit  for 
the  impression  of  effluvia.  This  membrane  adheres  to  the 
periosteum,  to  the  sinuses,  to  the  lachrymal  sacs,  Eusta- 
chian tubes,  pharynx,  and  palate,  and  is  intended  to  stop 
any  foreign  body  which  may  be  mixed  with  the  air.  The 
pituitary  membrane  is  extremely  vascular,  and  over  the 
whole  of  it  is  distributed  filaments  of, — 


Fig.  55. 


ORGANS  OF  SENSATION. 


165 


h,  Fig.  55,  the  fifth  pair  of  nerves,  which  endue  the 
membrane  with  ordinary  sensibility.  The  distribution  of  the 
first  nerve,  a,  d,  the  olfactory,  is  more  limited.  The  latter 
perforates  the  cribriform  plate  of  the  ethmoid  bone,  and 
spreads  in  numerous  filaments  over  the  septum  narium, 
and  surface  of  the  upper  turbinated  bones  ; this  nerve  is 
the  essential  organ  of  smell,  and  conveys  a perception  of 
odors  to  the  sensorium. 

The  maxillary  and  sphenoid  sinuses,  and  the  ethmoid 
cells,  open  into  the  nasal  cavity,  and  are  lined  by  a con- 
tinuation of  the  mucous  membrane  just  described. 


MECHANISM  OF  SMELL. 

A great  many  substances  in  nature  emit  certain  particles 
of  extreme  tenuity,  which  are  carried  by  the  air,  often  to  a 
great  distance  ; these  particles  constitute  odors  ; the  organ 
of  smelling  is  destined  to  perceive  and  appreciate  them  ; 
thus  an  important  relation  is  established  between  animals 
and  other  bodies.  The  mechanism  by  which  we  smell,  is 
extremely  simple  : it  is  only  necessary  that  the  odoriferous 
particles  should  be  detained  upon  the  pituitary  membrane, 
particularly  in  the  parts  where  it  receives  the  filaments  of 
the  olfactory  nerve.  The  nose  also  contributes  to  the  gen- 
eral purposes  of  respiration  and  the  modulation  of  the 
voice,  and  receives  the  superabundant  fluid  from  the  ex- 
ternal surface  of  the  eyes. 


166 


ORGANS  OF  SENSATION. 


CHAP.  IV. 

\ 

THE  TONGUE,  OR  ORGAN  OF  TASTE. 

The  tongue  is  a muscular  organ,  possessing  great  mo- 
bility, and  is  the  principal  organ  of  taste ; but  this  is  not 
its  only  use,  for  it  is  the  chief  instrument  of  speech,  and 
contributes  to  the  acts  of  sucking,  mastication,  and  deglu- 
tition. 

The  muscular  portion  of  the  tongue  forms  the  greater 
part  of  its  substance,  and  is  composed  of  the  fibres  of  the 
stylo-glossi,  the  hyo-glossi,  and  the  genio-glossi  muscles, 
which  have  already  been  described  : beneath,  and  on  each 
side  also,  are  two  parallel  fasciculi  of  fibres,  which  are 
named  the  lingual  muscles.  All  these  muscles,  however, 
have  their  fibres  interwoven  in  a most  inextricable  manner. 
In  the  upper  part  of  the  tongue,  there  are  interposed  small 
adipose  globules. 

At  the  centre  of  this  fleshy  tissue  there  is  a fibro-carti- 
laginous  septum,  which  gives  attachment  to  the  muscular 
fibres. 

The  mucous  membrane,  which  lines  the  whole  interior 
of  the  mouth,  passes  to  the  under  surface  of  the  tongue, 
forming  in  the  centre  a fold  which  is  named  the  freenum 
lingua;.  The  same  membrane  then  extends  on  each  side, 
beneath  the  tongue,  ascends  upon  its  edges,  passes  over  its 
upper  surface,  and  forms  three  folds  near  the  epiglottis. 

On  the  upper  surface  of  the  tongue  the  mucous  mem- 
brane presents  a very  different  appearance  to  that  on  its 
inferior  surface ; there  it  assumes  a distinct  epidermis, 
under  which  is  a tissue  formed  of  numberless  vessels  and 
nerves,  which  constitute  a net-work,  surrounding  the  pa- 


ORGANS  OF  SENSATION. 


167 


pillse  and  mucous  follicles,  and  which  give  to  the  tongue 
the  red  color  peculiar  to  it.  The  upper  surface  is  render- 
ed rough  and  uneven  by  the  existence  of  a very  great 
number  of  projections  differing  in  their  form.  These  are 
X\ie  papilla,  which  may  be  distinguished  into  three  kinds. 

1.  lenticular  papilla  \diry  \n  number  from  nine  to 
fifteen  ; they  are  observed  only  at  the  posterior  part  of  the 
tongue,  arranged  in  oblique  lines,  like  the  letter  v,  and 
meeting  at  a considerable  depression,  termed  the  foramen 
ccecum  of  Morgagni,  by  whom  it  was  first  described. 

The  lenticular  papillae  are  generally  spherical  or  oval  ; 
they  are  not  like  the  other  papillae,  organs  of  taste,  but  are 
simply  mucous  follicles,  which  open  upon  the  tongue  by 
very  small  orifices. 

2.  The  fungiform  papilla,  Fig.  56,  of  a 
whitish  appearance,  are  disseminated  irregu- 
larly near  the  edges  of  the  tongue ; they 
present  a rounded  flattened  head,  supported 
by  a narrow  pedicle. 

3.  The  conical  papilla.  Fig.  57,  or  papilla 
media. — These  are  by  much  the  most  nu- 
merous, and  occupy  almost  the  whole  upper 
surface  of  the  tongue,  becoming  gradually 

shorter  at  the  sides,  and  longer  and  more  abundant  at  the 
apex,  where  the  sensation  of  taste  is  most  acute. 

These  papillae  resemble  small  cones,  attached  to  the 
tongue  by  their  base,  and  free  at  their  summit ; they  are 
placed  close  to  each  other,  but  at  many  parts  leave  irregu- 
lar intervals  in  the  form  of  clefts. 

The  filiform  papilla.  Fig.  58,  are  observed 
at  the  edges  of  the  tongue  ; they  assume  a 
shred-like  appearance,  and  are  of  a similar 
fabric  to  the  last. 


Fig.  58. 


Fig.  56. 


168 


ORGANS  OF  SENSATION. 


Fig.  59. 

d 


The  nerves  of  the  tongue,  as  we  may  observe  in  the  an- 
nexed figure,  are  very  abundant,  and  are  furnished  by,  6,  e, 
tlie  inferior  maxillary  ; c,  the  glosso-pharyngeal ; and,  a, 
the  hypoglossal  nerves. 

Behind  the  fringes  formed  under  the  tongue,  we  perceive 
an  amygdaloid  granular  mass,  amply  supplied  by  blood- 
vessels, and  by  filaments  of  the  lingual  nerve. 

TASTE. 

Although  the  tongue  is  the  principal  organ  of  taste, 
the  lips,  the  internal  surface  of  the  cheeks,  the  palate, 
and  even  the  teeth  are  sensible  to  the  impression  of  sapid 
bodies. 

To  excite  a sensation  of  taste,  a substance  must  be  in  a 
liquid  state : to  promote  this  object,  when  a solid  is  placed 


ORGANS  OF  SENSATION. 


169 


in  the  mouth,  the  saliva  is  observed  to  flow  abundantly, 
and  its  sapid  qualities  are  perceived  in  proportion  as  it  dis- 
solves ; and  there  are  many  substances  which  we  cannot 
perfectly  taste  unless  their  fumes  ascend  into  the  cavity  of 
the  nostrils : indeed,  sensations  of  taste  are  not  perfect 
until  the  mouth  is  closed,  and  the  tongue  pressed  against 
the  palate,  by  which  means  the  sapid  body  is  brought  more 
immediately  into  contact  with  the  surface  of  the  tongue, 
and  perhaps  forced  into  the  nervous  membrane,  at  the  same 
time  that  the  fumes  are  driven  through  the  posterior  fauces 
into  the  nasal  cavities. 

The  choice  of  food  entirely  depends  on  the  taste  ; joined 
to  smell,  it  enables  us  to  distinguish  between  substances 
which  are  hurtful,  and  those  that  are  nutritious. 


CHAP.  V. 


T H E S K I N . 

The  skin  is  a dense  membrane  of  variable  thickness, 
according  to  the  part  which  it  covers  ; it  is  very  flexible, 
and  envelopes  the  whole  body  ; at  the  circumference  of 
the  apertures,  as  at  the  nose,  the  mouth,  etc.  it  is  continu- 
ous with  the  mucous  membrane  which  lines  those  cavities. 

The  skin  is  composed  of  three  very  distinct  layers  ; the 
dermis,  or  chorion,  the  rete  mucosum,  and  the  epidermis,  or 
cuticle. 


VOL.  II. 


22 


170 


ORGANS  OF  SENSATION. 


The  external  surface  of  the  skin  is  covered  by  a vast 
number  of  small  projections,  resembling  papillae,  and  it 
is  furrowed  by  a multitude  of  wrinkles,  some  of  which 
are  occasioned  by  the  action  of  muscles,  as  in  the  fore- 
head, the  hand,  and  the  sole  of  the  foot ; others  are  produ- 
ced by  the  flexure  of  joints,  or  by  the  rows  of  papillae,  as 
we  observe  at  the  extremities  of  the  fingers. 

This  surface  of  the  skin  presents  a multitude  of  pores, 
very  visible  by  the  aid  of  a microscope  ; it  has  been  ques- 
tioned whether  these  pores  are  the  terminations  of  exha- 
lent  vessels,  out  of  which  the  drops  of  sweat  issue  ; but 
they  may  be  considered  as  perforations  made  by  the  excre- 
tory ducts  of  sebaceous  follicles,  or  by  the  hairs. 

1.  THE  DERMIS. 

The  dermis  is  the  thickest  layer  of  the  skin,  and  is  form- 
ed of  fibres,  interwoven  in  an  inextricable  manner,  and  is 
so  plentifully  furnished  with  blood-vessels  and  nerves,  that 
the  smallest  puncture  cannot  be  made,  in  any  part  of  it, 
without  occasioning  pain  and  a discharge  of  blood. 

The  dermis  is  strong  and  elastic,  and  forms  the  most 
substantial  part  of  the  skin  ; indeed,  it  is  that  part,  in  quad- 
rupeds, of  which  leather  is  made. 

The  outer  part  is  very  compact,  the  inner  more  loose, 
and  it  gradually  degenerates  into  the  common  cellular 
tissue. 

The  dermis  is  covered  in  all  its  regions  with  more  or  less 
distinct  prominences,  and  irregular  depressions,  which  ap- 
pear through  the  epidermis.  The  asperities  are  named  the 
papillae,  and  are  divided  by  a series  of  small  depressions, 
to  the  number  of  four  or  five  in  the  extent  of  a line. 
On  the  points  of  the  toes,  and  on  the  tips  of  the  fingers, 
the  papillae  generally  take  a somewhat  spiral  and  parallel 
direction. 


ORGANS  OF  SENSATION. 


171 


Blood-vessels  twine  in  the  subcutaneous  cellular  tissue, 
and  project  an  infinitude  of  small  branches,  which  pene- 
trate into  the  remotest  areolae  of  the  dermis,  unite  in  a 
variety  of  ways,  cross  the  external  surface,  and  finally  give 
rise  to  that  capillary  net,  which  I shall  describe  in  speaking 
of  the  rete  mucosum. 

The  nerves  are  distributed  nearly  in  the  same  order  as 
the  blood-vessels  ; there  is  a subcutaneous  stratum  of  the 
nervous  system  from  which  pass  all  the  filaments  which 
penetrate  the  dermis.  These  filaments  frequently  unite 
and  insinuate  themselves  into  the  internal  areolae,  and 
undoubtedly  terminate  in  giving  origin  to  the  papillae.  In 
the  hand,  and  at  the  points  of  the  fingers,  where  the  papillae 
are  remarkably  conspicuous,  there  is  a larger  proportion  of 
subcutaneous  nerves  than  in  any  other  part  of  the  body  ; 
and  it  cannot  be  doubted  that  the  soles  of  the  feet,  the 
palms  of  the  hands,  and  the  tips  of  the  fingers,  are  gifted 
with  much  more  sensibility  than  any  other  parts. 

2.  THE  RETE  MUCOSUM. 

This  tissue  lies  immediately  under  the  dermis,  and  is 
the  chief  cause  of  that  variety  of  color  which  characterises 
the  natives  of  different  climates,  and  different  people  of  the 
same  climate  ; being  white,  or  rather  of  a light  gray  in  the 
European,  brown  in  the  Asiatic,  and  black  in  the  African. 
And,  on  account  of  the  thinness  and  transparency  of  the 
dermis,  the  color  of  the  rete  mucosum  appears  through  it. 

The  rete  mucosum  then  may  be  conceived  as  a general 
capillary  system,  enveloping  the  cutaneous  organ,  and 
forming,  in  common  with  the  papillae,  a stratum  interposed 
between  the  dermis  and  the  epidermis.  In  different  sub- 
jects it  has  a different  hue,  forming  the  complexion  of  the 
individual,  and  there  is  every  intermediate  color  from  the 


172 


ORGANS  OF  SENSATION. 


swarthy  hue  of  the  negro,  to  the  fairest  skin  of  the  Euro- 
pean. Hence,  the  comple.vion  depends  on  the  substance 
which  exists  in  the  very  minute  vessels  of  the  skin. 

It  is  likewise  the  cause  of  the  difference  of  color  in  dif- 
ferent parts  of  the  body  of  the  same  person,  and  is  compo- 
sed, according  to  Gaultier,  of  four  distinct  layers ; the 
first  counting  from  within  outwards,  is  formed  of  blood- 
vessels arranged  like  granulations,  on  the  asperities  of  the 
dermis  ; the  second  is  whitish,  and  applied  upon  the  for- 
mer, in  the  irregularities  of  the  dermis,  and  there  are 
numerous  prolongations  of  this  layer  which  penetrate  into 
the  substance  of  the  dermis ; the  third  layer  is  composed 
of  minute  convex  bodies,  containing  the  coloring  matter  of 
the  skin  ; the  fourth  layer  is  white,  of  extreme  tenuity, 
perforated  by  tlie  hairs,  and  adherent  to  the  epidermis. 

3.  THE  EPIDER.MIS. 

The  ejjidermis,  or  cuticle,  is  the  most  superficial  layer, 
and  is  separated  from  the  dermis  by  the  rete  mucosum. 
It  presents  all  the  wrinkles  and  furrows  which  have  been 
mentioned  in  the  description  of  the  outer  surface  of  the 
dermis ; it  is  thin,  and  transparent,  and  formed  of  numer- 
ous scales  in  close  apposition  with  one  another.  The  inner 
surface  is  very  firmly  attached  to  the  dermis,  on  removing 
it  by  maceration,  we  observe  a multiplicity  of  small  pro- 
longations, which  appear  to  be  nothing  more  than  processes 
which  line  the  passages  through  which  hairs  grow  and  the 
sebaceous  follicles  open. 

A great  number  of  sebaceous  follicles  are  seated  under  the 
skin,  and  open  by  small  ducts  on  its  surface  ; Mr  Cheva- 
lier* counted  one  hundred  and  forty  in  the  space  of  a quar- 

* Lectures  on  the  General  Structure  of  the  Human  Body,  delivered  at  the 
Royal  College  of  Surgeons. — p.  18C. 


ORGANS  OF  SENSATION. 


173 


ter  of  an  inch,  which  will  make  one  hundred  and  twenty 
millions  on  the  surface  of  the  whole  body.  These  follicles, 
or  glands,  secrete  an  oily  fluid  which  serves  to  lubricate  the 
skin,  and  defend  it  from  the  inclemency  of  the  weather,  or 
from  the  effects  of  friction. 

Immense  multitudes  of  perforations  have  been  supposed 
to  exist  in  the  epidermis,  for  the  purpose  of  allowing  the 
perspirable  matter  to  escape  from  the  body.  _ But  are  there 
any  in  reality  ? A microscope  of  high  powers  will  not  de- 
tect them  ; we  can  only  discern  those  apertures  which  be- 
long to  the  hairs,  and  the  sebaceous  follicles.  The  serum, 
produced  by  a blister,  will  not  exude  from  within,  nor  will 
water  or  other  fluids  penetrate  from  without.  How  then 
is  the  office  of  perspiration  carried  on  through  the  cuticle  ? 
Instead  of  porosity,  this  appearance  results  from  an  infinite 
number  of  velaminse,  regularly  arranged,  of  exquisite  tenu- 
ity, presenting  a follicular  appearance,  and  separated  from 
each  other  by  filaments  crossing  in  a thousand  different 
directions.  The  terminal  vessels  of  the  cutaneous  appara- 
tus transmit  the  perspiration  through  this  tissue,  without 
the  inconvenience  of  perforated  pores.  Perspiration  then 
is  a secretion  produced  by  the  action  of  the  sudatory  ves- 
sels, and  not  an  exudation,  and  the  skin  constitutes  one 
wide  and  diffused  perspiratory  gland  ; a subtile  fluid  is 
separated  from  the  circulation  by  it,  from  the  invisible 
vapor  of  perfect  health  and  ease,  to  the  profuse  and  colli- 
quative sweat  of  a languishing  hectic.  The  skin,  there- 
fore, seems  the  natural  and  appropriate  recipient  of  the 
capillary  vessels  of  the  cutaneous  secretion,  which  it  trans- 
mits through  that  exquisitely  fine  gauze  of  the' epidermis. 
Perspiration  liberates  from  the  blood  superfluous  animal 
gas,  and  water;  and  by  its  copious  evaporation  in  summer, 
and  its  partial  suppression  in  winter,  it  regulates  the  tem- 
perature of  our  bodies,  and  thus  the  skin  acts  as  the  safety- 
valve  of  life  and  health. 


174 


ORGANS  OF  SENSATION. 


E.xhalents,  absorbent  vessels,  and  hairs  pass  through 
the  epidermis,  but  no  blood-vessels  have  been  traced  in  it, 
either  by  the  eye  or  by  the  assistance  of  glasses : it  pos- 
sesses, therefore,  none  of  the  properties  of  life : it  •wears 
away  and  is  renewed  continually,  and  its  thickness  lessens 
or  augments,  as  it  is  needed  ; it  becomes  hard  and  thick 
on  the  hands  of  the  laborer,  and  soft  and  delicate  on 
the  hands  of  those  who  are  occupied  in  lighter  employ- 
ments. 


THE  SENSE  OF  TOUCH. 

This  is  the  fifth  sense,  and  must  be  included  in  the 
description  of  the  skin.  None  of  the  vertebrata  inferior 
to  man  are  endowed  with  the  special  organ  of  touch  ; and 
although  the  general  surface  is  in  most  animals  an  organ 
of  sense,  the  distinct  faculty  of  touch  is  entirely  wanting, 
or  exists  in  a very  modified  degree.  It  is  in  the  sense  of 
touch,  says  Cuvier,  that  we  excel  every  other  animal,  why? 
Because  this  sense  is  quite  different  from  the  others  ; this 
is  consequent  to  them,  and  rectifies  their  errors : we  feel, 
because  we  have  seen,  heard,  tasted,  or  smelt  the  objects. 
Touch  is  voluntary,  and  reflection  is  necessary  to  exercise 
it,  while  the  other  four  require  none.  Light,  sound,  etc. 
may  strike  their  respective  organs  unnoticed,  but  we  touch 
nothing  without  a preliminary  act  of  the  intellectual  func- 
tions. 

Sensibility  to  cold  and  various  stimuli  does  not  prove 
that  the  lower  grades  of  animals  have  the  sense  of  touch  ; 
our  own  species  inherits  this  common  sensibility,  which  we 
maintain  essential  to  all  other  organized  structures  ; but, 
in  addition  to  this,  we  possess  the  special  sense  of  touch, 
which  enables  us  to  ascertain  the  properties  of  bodies,  for 
almost  all  the  physical  properties  of  bodies  are  capable  of 


ORGANS  OF  SENSATION. 


175 


acting  on  the  organs  of  touch  ; form,  dimensions,  loco- 
motion, and  vibration,  are  all  appreciated  by  the  organ  of 
touch. 

The  whole  cuticular  surface  may  be  said  to  have  a mo- 
dified sense  of  touch,  and  this  kind  of  feeling  is  likewise 
shared  by  the  mucous  membrane  of  the  eyes,  nose  and 
mouth,  the  laryn.v,  rectum,  and  the  external  genital  organs. 
But  the  hand  only  can  be  truly  designated  as  the  organ  of 
touch ; the  hand  is  expressly  constructed  for  the  purpose 
of  examining  the  qualities  of  objects  : the  tips  of  the 
fingers  especially  have  practically  the  finest  discrimination 
of  the  tangible  qualities  of  bodies.  This  delicacy  of  touch 
in  the  fingers  has  given  man  a great  advantage  over  the 
animals  : his  touch  is  so  delicate  that  it  has  been  consider- 
ed the  source  of  his  intelligence.  This  sense  is  capable  of 
arriving  at  a very  great  degree  of  perfection,  as  is  seen  in 
many  professions ; and  Magendie  observes,  that,  “ for 
medical  men,  a very  delicate  sense  of  touch  is  absolutely 
necessary.”  This  property  then,  of  the  nervous  system, 
as  before  mentioned,  which  depends  on  the  extreme  pulpy 
distribution  of  the  posterior  roots  of  the  spinal  nerves,  can 
be  assigned  only  to  man. 

THE  HAIR. 

Hair  exists  on  almost  all  parts  of  the  surface  of  the 
body  and  limbs,  except  the  palm  of  the  hand  and  the  sole 
of  the  foot. 

The  head  is  that  part  wherein  the  hair  is  most  abun- 
dant ; it  occupies  the  whole  space  corresponding  with  the 
occipital,  the  parietal,  the  squamous  portion  of  the  tempo- 
ral, and  the  upper  part  of  the  frontal  bones.  It  seems  to 
be  provided  as  a protection  against  mechanical  injuries  of 
the  head.  The  hair  on  the  face  and  other  parts  is,  in  gen- 
eral, much  less,  though  still  in  great  quantity. 


176 


ORGANS  OF  SENSATION. 


The  difference  in  the  nature  of  the  hair  considerably  in- 
fluences it  length  ; lank  hair  is  generally  the  longest.  The 
more  it  curls  the  shorter  it  is,  as  exemplified  in  the  African 
and  even  in  Europeans. 

The  color  of  the  hair  varies  considerably,  according  to 
the  difterent  countries,  latitudes  and  climates.  Naturalists 
have  considered  the  color  of  the  hair,  as  well  as  that  of  the 
skin,  as  forming  one  of  the  characteristic  distinctions  of  the 
human  races. 

The  eyehroivs  form  arches  to  shade  the  eyes,  and  their 
motions  are  intended  to  protect  them  from  the  too  power- 
ful impression  of  luminous  beams.  Their  actions  also  are 
very  expressive  of  the  passions  and  mental  emotions, 
which  affect  the  individual.  Painters  have  paid  much 
more  attention  than  anatomists  to  the  varied  position  of 
the  eyebrows. 

The  eyelashes  have  a similar  use ; they  moderate  the 
light,  and  likewise  guard  the  eye  from  substances  floating 
in  the  atmosphere. 

The  hair  on  the  chin  and  upper  lip  is  the  peculiar  attri- 
bute of  the  male ; and  appears  towards  the  period  of 
virility,  when  the  animal  powers  increase. 

The  hair  on  the  trunk  varies  most  astonishingly ; some 
men  are  almost  completely  hairy,  whilst  others  are  not  at 
all  so.  Generally  speaking,  the  fore  part  of  the  body  pos- 
sesses much  more  than  the  back  part : in  men  it  is  partic- 
ularly met  with  along  the  median  line  of  the  chest. 

In  both  sexes  a considerable  quantity  shades  the  genital 
organs. 

The  hair  on  the  limbs,  in  man,  is  abundant  on  the  whole 
surface  : the  proportion  is  the  same  in  all,  but  its  length 
and  fineness  vary  considerably.  In  some  it  consists  of  a 
mere  down,  in  others  it  is  coarse  and  thick,  giving  to  the 
limbs  a hairy  aspect. 


ORGANS  OF  SENSATION. 


177 


ORGANIZATION  OF  THE  HAIR. 

The  hair  may  vary  in  respect  to  form,  length,  and  fine- 
ness, but  its  organization  is  the  same  in  all.  It  generally 
arises  from  the  subcutaneous  cellular  tissue  : every  individ- 
ual hair  originates  in  a bulb,  or  root, and  each  bulb  has  two 
capsules,  containing  an  oily  fluid  between  them,  which  gives 
color  to  the  hair;  a deficiency  of  this  is  supposed  to  occa- 
sion a change  of  the  color,  and  the  whiteness  we  observe 
in  advanced  life. 

In  general  the  color  of  the  hair  has  some'relation  to  the 
rete  mucosum  ; as  in  the  negro,  the  hair  corresponds  with 
the  tint  of  the  skin,  and  in  a person  with  light  or  with  dark 
colored  hair,  there  is  a florid  or  a dark  complexion. 

The  hairs  in  passing  from  the  skin,  are  supposed  to  carry 
with  them  a sheath  of  the  epidermis,  which  is  thin,  but 
hard,  and  so  transparent,  as  to  allow  the  color  of  the  hair 
to  appear  through  it.  With  the  aid  of  a good  glass  we 
may  observe  canals  for  containing  their  nourishing  fluid, 
termed  the  medulla,  which  constitutes  the  coloring  matter 
of  the  hair.  The  chemical  properties  of  the  hair  appear 
to  be  of  the  same  nature  as  the  epidermis,  cartilage  and 
the  nails. 

The  hair  serves  in  general  for  ornament,  to  retain  animal 
heat,  or  to  protect  the  diflerent  parts  on  or  near  which  it  is 
situated. 

THE  NAILS. 

The  fingers  are  provided,  at  their  extremities,  with  a 
hard,  transparent,  and  flexible  kind  of  plate,  of  a similar 
nature  to  that  of  horn. 

The  upper  part  of  the  nail,  which  is  concealed,  forms 

2,3 


VOL.  II. 


178 


ORGANS  OF  SENSATION. 


nearly  a sixth  part  of  its  whole  extent : its  surface  adheres 
strongly  to  the  epidermis,  which,  to  fix  it,  is  disposed  in 
the  following  manner:  — after  having  covered  the  portion 
of  the  finger,  corresponding  to  the  last  joint,  it  is  reflected 
over  the  concave  border,  where  the  skin  ends,  and  the  nail 
begins  to  emerge  ; the  epidermis  having  formed  a kind  of 
ridge,  is  again  reflected,  insinuates  itself  between  the  skin 
and  the  nail,  and  adheres  to  the  concave  surface  without 
being  confounded  with  it  ; for  it  is  easily  removed  by 
maceration  or  with  the  dissecting  knife.  Thus  the  nail  is 
placed  in  a folding  of  the  skin  ; there  is,  however,  a cuti- 
cular  covering  to  it,  which  appears  to  be  derived  from  a 
lamina  of  the  epidermis. 

The  nails  strengthen  and  defend  the  ends  of  the  fingers 
and  toes  ; they  afford  a support  to  the  ends  of  the  fingers 
in  grasping  bodies,  and  they  are  particularly  useful  in  taking 
hold  of  minute  objects. 


CHAP.  VI. 

MUSCULAR  SENSATION. 

To  the  sensitive  department  of  the  fifth  pair,  and  the 
compound  spinal  nerves,  is  assigned  muscular  sensation. 
This  is  the  sixth  sense.  All  our  conceptions  of  weight 
and  resistance,  and  motion  in  general,  are  derived  from  our 
muscles.  The  muscular  system,  then,  may  be  considered  a 


ORGANS  OF  SENSATION. 


179 


distinct  organ  of  sense  as  well  as  motion ; each  motion  of 
the  invisible  muscles  is  accompanied  with  a certain  feeling, 
which  may  indeed  be  complex,  as  arising  from  various 
muscles,  but  which  is  considered  by  the  mind  as  one,  and 
it  is  this  peculiar  feeling,  attending  the  action  of  the  mus- 
cular fibres,  which  we  distinguish  from  every  other  sensa- 
tion. To  e.xemplify  this,  I might  refer  to  the  state  of  the 
muscles  in  cramp  of  the  limbs,  and  in  rheumatic  affections; 
in  such  morbid  conditions  their  structure  becomes  painfully 
sensible.  But  let  us  call  to  mind  the  phenomenon  which 
every  one  must  have  experienced,  I mean  the*  feeling  of 
fatigue  ; this  is  a muscular  sensation’:^  a sensation  of  which 
the  muscles  are  the  organs,  as  much  so  as  the  eye, 
and  the  ear,  are  the  organs  of  sight  and  hearing.  Every 
bodily  effort  depends  on  muscular  contraction ; and  long 
and  frequent  contractions,  that  is,  continued  exercise,  oc- 
casion a peculiar  uneasiness  which  demands  repose.  Pow- 
erful and  protracted  exertions  produce  painful  sensations  to 
the  muscular  sense ; a more  moderate  degree  of  exercise  is 
attended  with  agreeable  sensations.  With  a healty  state 
of  body,  there  is  a muscular  pleasure  in  exertion.  Thus 
the  child  who  is  not  playful,  is  not  healthy.  There  is  a 
muscular  gratification,  if  I may  so  express  myself,  in  every 
limb,  in  the  games  and  pastimes  of  the  school  boy. 

Dr  Brown,  without  being  aware  that  there  was  a pecu- 
liar set  of  nerves  appropriated  to  muscular  sensation, 
observes,  that  “ nature  in  the  other  animals,  whose  sources 
of  general  pleasure  are  more  limited,  has  converted  their 
muscular  system  into  an  organ  of  delight.  It  is  not  in 
search  of  richer  pasture  that  the  horse  gallops  over  the 
field,  or  the  goat  leaps  from  rock  to  rock,  it  is  for  the  lux- 
ury of  the  exercise  itself.  It  is  this  appearance  of  active 
life  which  spreads  a charm  over  every  little  group  with 
which  the  Deity  animates  the  scenery  of  nature.”  We 
may,  therefore,  consider  that  the  muscular  system  is  not 


180 


ORGANS  OF  SENSATION. 


merely  the  living  machinery  of  motion,  but  that  it  is  also 
truly  an  organ  of  sense. 

The  muscular  sensation  commences  in  infancy ; there  is 
a feeling  of  clanger  when  the  child  is  first  tossed  in  the 
nurse’s  arms,  and  afterwards,  when  it  essays  to  walk,  there 
is  evidently  an  apprehension  of  falling.  Sir  C.  Bell*  has 
shown  that  we  have  a muscular  sense,  and  that  without  it 
we  could  have  no  guidance  of  our  frame ; that  we 
could  not  command  our  muscles  in  standing,  far  less  in 
walking,  leaping,  or  running,  had  we  not  a perception  of 
the  condition  of  the  ^muscles. 

Without  a sense  of  muscular  action  or  consciousness  of 
the  effort  made,  the  proper  sense  of  touch  could  hardly  be 
an  inlet  to  knowledge.  The  property  of  the  hand  in  as- 
certaining the  size,  the  weight,  the  form,  the  hardness  and 
softness,  the  roughness  or  smoothness  of  objects,  results 
from  the  combined  perception  — through  the  sensibility  of 
the  proper  organ  of  touch,  and  the  motion  of  the  hand, 
arm  and  fingers.  But  the  motion  of  the  fingers  is  especially 
necessary  to  the  sense  of  touch  ; they  bend,  extend,  or  ex- 
pand like  palpa,  with  the  advantage  of  embracing  the  ob- 
ject, and  feeling  on  all  its  surfaces  ; sensible  to  its  solidity 
and  to  its  resistance  when  grasped  ; moving  round  it  and 
gliding  over  its  surface,  and,  therefore,  feeling  every  asperity. 

The  same  author  has  given  an  admirable  description  of 
the  pleasures  arising  from  the  muscular  sense. 

“ The  exercise  of  the  muscular  frame  is  the  source  of 
much  of  the  knowledge  which  is  usually  supposed  to  be 
obtained  through  the  organs  of  sense  ; and  to  this  source, 
also,  we  must  trace  some  of  our  own  chief  enjoyments. 
We  may,  indeed,  affirm  that  it  is  benevolently  provided 
that  vigorous  circulation,  and,  therefore,  the  healthful  con- 

* Biidgevvaler  Treatise.  On  the  Hand,  its  Mechanism  and  vital  Endow- 
iTieuts. — p.  189. 


ORGANS  OF  SENSATION. 


181 


dition  both  of  the  mind  and  the  body,  shall  result  from 
muscular  exertion  and  the  alternation  of  activity  and  repose. 

“ The  pleasure  which  arises  from  the  activity  of  the  body 
is  also  attended  by  gratification  from  the  exercise  of  a 
species  of  power  — as  in  mere  dexterity,  successful  pursuit 
in  the  field,  or  the  accomplishment  of  some  work  of  art. 
This  activity  is  followed  by  weariness  and  a desire  for  rest, 
and  although  unattended  with  any  describable  pleasure  or 
local  sensation,  there  is  diffused  through  every  part  of  the 
frame,  after  fatigue  and  whilst  the  active  powers  are  sinking 
into  repose,  a feeling  almost  voluptuous.  To  this  succeeds 
the  impatience  of  rest,  and  thus  we  are  urged  to  the  alter- 
nations which  are  necessary  to  health,  and  invited  on  from 
stage  to  stage  of  our  existence. 

“ We  owe  other  enjoyments  to  the  muscular  sense.  It 
would  appear  that  in  modern  times  we  know  comparatively 
little  of  the  pleasures  arising  from  motion.  The  Greeks, 
and  even  the  Romans,  studied  elegance  of  attitude  and 
movement.  Their  apparel  admitted  of  it,  and  their  exer- 
cises and  games  must  have  led  to  it.  Their  dances  were 
not  the  result  of  mere  exuberance  of  spirits  and  activity ; 
they  studied  harmony  in  the  motion  of  the  body  and  limbs, 
and  majesty  of  gait.  Their  dances  consisted  more  of  the 
unfolding  of  the  arms,  than  the  play  of  the  feet:  ‘their 
arms  sublime  that  ffoated  on  the  air.’  The  Pyrrhic  dances 
were  elegant  movements,  joined  to  the  attitudes  of  combat, 
and  performed  in  correct  coincidence  with  the  expression 
of  the  music.  The  spectators  in  their  theatres  must  have 
had  very  different  associations  from  ours,  to  account  for 
the  national  enthusiasm  arising  from  music,  and  their  rage 
excited  by  a mere  error  in  time. 

“ This  reminds  us  that  the  diversions  in  music  in  some 
degree  belong  to  the  muscular  sense.  A man  will  put  down 
his  staff  in  regulated  time,  and  the  sound  of  his  steps  will 
fall  into  a measure,  in  his  common  walk.  A boy  striking 


182 


ORGANS  OF  SENSATION. 


the  railing  in  mere  wantonness,  will  do  it  with  a regular 
succession  of  blows.  This  disposition  of  the  muscular 
frame  to  ])ut  itself  into  motion,  with  an  accordance  of  time, 
is  the  source  of  much  that  is  pleasing  in  music,  and  aids 
the  effect  of  melody.  There  is  thus  established  the  closest 
connection  between  the  enjoyments  of  the  sense  of  hear- 
ing, and  the  exercise  of  the  muscular  sense.” 


CHAP.  VII. 

VISCERAL  SENSATION. 

I HAVE  elsewhere  stated  that  the  ganglionic  department 
of  the  nervous  system  belongs  to  organic  life.  The  whole 
series  of  actions  resulting  from  this  department  are  instinc- 
tive. And  we  are  conscious  that  the  nerves  of  the  ganglia 
are  the  seat  of  certain  sensations.  This  is  the  seventh  or 
VISCERAL  sense.  The  ganglionic  nerves,  throughout  the 
whole  animal  kingdom,  preside  over  the  organic  or  vegeta- 
tive functions,  so  as  to  control  and  direct  their  operation  ; 
but  their  sensation  or  perception,  in  man,  is  connected  fre- 
quently with  certain  affections  of  the  mind.  Magendie 
said  “ the  passions  were  the  triumph  of  the  viscera  over 
the  intellect.”  It  is,  however,  with  great  diffidence  that  I 
proceed  to  a description  of  this  ganglionic  or  visceral  sen- 
sation, although  I am  convinced  of  its  existence. 

1st.  In  the  viscera  of  the  chest;  — strong  mental  emo- 


ORGANS  OF  SENSATION. 


183 


tion,  as  anger,  first  exalts,  and  then  exhausts  the  powers- of 
the  heart : and  extreme  grief,  says  Bichat,  has  been  known 
so  to  debilitate  the  circulatory  powers,  as  to  render  them 
incapable  of  returning  to  their  usual  condition.  Desault, 
the  late  chief  surgeon  of  the  Hotel  l)ieu,  has  remarked, 
that  diseases  of  the  heart,  and  aneurisms  of  the  aorta, 
were  augmented  in  number  during  the  Revolution,  in  pro- 
portion to  the  evils  which  it  produced.  The  united  testi- 
mony of  mankind  concurs  in  referring  all  the  finer  feelings 
(sensations)  to  the  heart ; and  this  view  of  the  subject  of 
visceral  sensation,!  imagine  must  be  confirmed  by  our  own 
individual  experience  and  perceptions.* 

Of  this  species  of  sensation  is  profound  sorrow  ; it  is 
felt  in  the  lungs  ; hence,  the  sense  of  oppression,  anxiety, 
suffocation,  and  involuntary  sighs,  which  visibly  agitate  the 
pulmonary  organs. 

2d.  The  abdominal  organs  possess  similar  visceral  sen- 
sation. The  stomach  is  affected  by  any  kind  of  trouble : 
frequently  it  will  cause  a painful  sensation  in  that  organ, 
and  an  interruption  of  the  digestive  process  ; and  the  sad 
forebodings  and  darker  affections  of  the  mind,  have  a sen- 
sible effect  on  the  digestive  organs. 

It  has  been  very  judiciously  observed  by  Haller,  that 
the  sensation  we  experience  in  parts  receiving  nerves  from 
the  ganglions  have  a peculiar  character ; that  they  do  not 
resemble  those  experienced  in  such  parts  as  are  supplied 
with  cerebral  nerves.  Broussais  ascribes  the  pleasure  and 
pain  which  accompany  the  exercise  of  the  intellectual  facul- 
ties, as  having  the  same,  seat  as  the  pleasure  and  pain  of 

*Dr  SpuRZHEiM  denies  that  the  feelings  depend  on  the  viscera  of  the  tho- 
rax or  abdomen.  The  influence  of  the  abdominal  and  thoracic  viscera  or 
the  manifestations  of  the  mind  is  only  mediate  ; their  functions  contribute 
to  the  organic  construction  of  the  brain  as  well  as  of  the  body  in  general, 
but  they  are  not  the  seat  of  the  affective  faculties.” 


184 


ORGANS  OF  SENSATION. 


the  passions  ; for  the  sensorium  cannot  feel  without  a cor- 
responding feeling  in  the  viscera. 

Are  not  hunger  and  thirst  also  instinctive  and  visceral 
sensations  ? Are  they  not  important  indications  to  the  in- 
dividual of  the  wants  of  the  animal  economy,  and  do  they 
not  incite  the  animal  to  acts  which  contribute  and  are 
essential  to  self-preservation?  And  the  solicitation  for  food 
and  drink  must  be  obeyed,  or  alienation  of  the  mind,  or 
death  of  the  body  must  ensue. 

Hunger  is  characterised  by  a peculiar  sensation  in  the 
region  of  the  stomach  ; there  is  a sense  of  drawing  and 
oppression  in  that  part,  and  when  the  cravings  of  hunger 
are  not  appeased,  it  amounts  to  severe  pain  in  the  stomach, 
and  a general  feebleness  of  the  whole  frame. 

It  might  be  easily  proved  that  all  the  abdominal  viscera 
are  capable  of  transmitting  impressions  to  the  brain,  with- 
out the  intervention  of  any  external  cause;  and  examples 
might  be  multiplied,  were  it  necessary,  to  establish  the 
theory  of  visceral  sensation,  without  referring  to  the  morbid 
states  to  which  the  internal  organs  are  liable'. 

The  ganglionic  visceral  feelings  are  instinctive,  and  con- 
stitute a separate  department  of  sense;  the  impressions 
conveyed  by  this  department  of  the  nervous  system,  to  the 
common  sensorium,  being  totally  dissimilar  to  those  which 
result  from  any  other  order  of  nerves.* 

*■  Tliere  are  several  species  of  sensation  resulting  from  the  ganglionic  de- 
partment, which,  in  an  elementary  work  of  this  kind,  cannot  be  discussed 
even  in  the  most  transitory  manner,  but  which  may  be  compressed  in  the 
generic  term,  visceral  sensation,  every  species  of  which  is  instinctive; 
namely,  sensations  determined  by  the  viscera,  and  which  solicit  the  nervous 
centre  to  execute  acts  necessary  for  the  exercise  of  their  functions. 


ART.  IX. 


ORGANS  OF  DIGESTION. 


THE  MOUTH. 

The  mouth  is  circumscribed  laterally  by  the  cheeks,  an- 
teriorly by  the  lips,  posteriorly  by  the  velum  palati,  above 
by  the  arch  of  the  palate,  and  below  by  the  tongue.  The 
cavity  of  the  mouth,  and  the  organs  which  it  contains,  are 
lined  by  a common  mucous  membrane. 

This  membrane  forms  a fold  opposite  the  symphysis  of 
the  chin,  which  is  named  the  frcenum  of  the  under  Up. 
The  mucous  membrane  passes  into  each  alveolus,  a pro- 
longation of  which  adheres  to  the  roots  of  the  teeth,  and 
indeed  lines  the  cavities  into  which  they  are  inserted.  Be- 
neath the  tongue  we  find  another  fold,  called  the  frcenum 
of  the  tongue.  This  membrane  is  then  continued  over  the 
epiglottis  into  the  larynx  and  pharynx. 

About  the  middle  of  the  lining  of  the  cheeks  we  observe 
the  orifice  of  the  parotid  duct,  and  in  other  parts  a great 
number  of  mucous  follicles. 

The  lips  are  principally  composed  of  muscles  which  have 
been  described ; they  are  covered  outwardly  by  the  com- 
mon integuments,  and  lined  within  by  the  membrane  of  the 
mouth. 


VOL.  II. 


-24 


186 


ORGANS  OF  DIGESTION. 


The  lips  possess  a small  proportion  of  adipose  tissue ; 
but  there  is  a considerable  quantity  generally  found  in  the 
cheeks,  which  give  shape  to  the  face. 


THE  PALATE. 

The  i)alate,  or  roof  of  the  mouth,  represents  a kind  of 
parabolic  arch ; a white  depressed  line  extends  from  the 
anterior  to  the  posterior  part  of  the  palate,  in  the  median 
line  of  the  body. 

On  the  arch  of  the  palate,  the  common  mucous  mem- 
brane is  much  more  dense  and  thick  than  on  the  other  parts 
of  the  mouth,  and  is  interspersed  with  small  perforations, 
which  are  the  orifices  of  mucous  follicles,  situated  between 
it  and  the  osseous  part  of  the  palate. 

The  glims  are  continuous  with  the  membrane  of  the 
palate,  and  are  formed  of  a similar  kind  of  compact  red 
tissue,  the  intimate  structure  of  which  it  is  difficult  to 
explain  : they  are,  however,  prolonged  into  the  alveolar 
cavities,  and  send  into  the  root  of  each  tooth  a bulbous 
process,  named  the  pulp  of  the  tooth. 

The  velum palati,  or  soft  palate,  is  a soft,  broad,  mobile 
partition,  situated  at  the  extremity  of  the  palate,  and  sepa- 
rating the  mouth  from  the  palate.  Its  upper  edge  is  ad- 
herent to  the  arch  of  the  os  palati ; its  lower  edge  is 
extended  over  the  root  of  the  tongue.  It  presents,  at  its 
middle  part,  a prolongation,  termed  the  uyiiZe ; which  forms 
the  inferior  edge  of  the  palate  into  a double  arch. 

The  velum  palati  acts  like  a valve,  in  preventing  what 
we  swallow  from  passing  into  the  nose. 

The  pillars  of  the  velum  palati  are  united  above,  but 
diverge  below,  and  are  separated  by  a triangular  space  in 
which  the  tonsils  are  lodged. 

The  tonsils  are  of  a light  red  color,  somewhat  of  the  size 


ORGANS  OF  DIGESTION. 


187 


/ 

and  figure  of  almonds  ; they  are  full  of  cells  which  com- 
municate with  each  other,  and  have  large  irregular  open- 
ings which  convey  a transparent  mucous  into  the  throat ; 
they  are  situated  between  the  anterior  and  the  posterior 
pillars  of  the  soft  palate,  and  close  by  the  sides  of  the  base 
of  the  tongue. 


THE  PHARYNX. 

The  pharynx  is  a funnel-shaped  musculo-membranous 
canal,  situated  behind  the  tongue  ; it  extends  from  the  base 
of  the  skull  to  near  the  middle  of  the  neck  ; it  rests  on  the 
vertebral  column,  and  on  its  sides  is  in  contact  with  the 
common  and  internal  carotid  arteries,  the  internal  jugular 
veins  and  the  pneumo-gastric  nerves.  It  is  connected  with 
those  different  parts  by  a cellular  tissue  of  a very  extensile 
character,  and  destitute  of  adipose  substance. 

Anteriorly,  on  a level  with  the  nasal  fossa  and  mouth, 
the  cavity  of  the  pharynx  is  open  ; opposite  the  commence- 
ment of  the  trachea,  it  contracts,  and  terminates  in  the 
cesophagus. 

The  pharynx  has  several  openings  by  which  it  commu- 
nicates with  the  neighboring  cavities ; two  of  these,  called 
the  posterior  nares,  lead  upwards  and  forwards  ; two  others, 
called  the  Eustachian  tubes,  proceed  laterally  to  the  ears  : 
one  passes  forward,  termed  the  fauces,  or  upper  part  of  the 
throat,  to  the  mouth  ; one  downwards,  through  the  larynx 
and  trachea,  to  the  lungs  ; and  another,  which  is  a contin- 
uation of  the  pharynx,  leads  directly  downwards  by  the 
oesophagus  to  the  stomach. 

The  muscles  of  which  it  is  composed  are  the  six  con- 
strictors, which  have  been  described  ; their  fibres,  which 
differ  in  their  obliquity,  form  planes  crossing  each  other  in 
different  directions.  See  vol.  I.  fig.  120. 


188 


ORGANS  OF  DIGESTION. 


A mucous  membrane  lines  the  whole  cavity  of  the  pharynx, 
which  has  a very  deep  red  tint.  It  is  smooth,  or  presents 
only  a few  inequalities,  arising  from  the  presence  of  the 
mucous  follicles. 

The  pharynx  receives  the  aliments  from  the  mouth,  and, 
by  the  action  of  its  muscles,  conveys  them  to  the  oesopha- 
gus. It  also  receives  the  air  we  inspire,  and  assists  in  the 
modulation  of  the  voice. 


THE  (ESOPHAGUS. 

The  oesophagus,  or  gullet,  is  a musculo-membranous 
canal,  extending  from  the  lower  part  of  the  pharynx  to  the 
upper  orifice  of  the  stomach. 

It  is  situated  between  the  trachea  and  the  vertebrae,  and 
in  the  neck  it  deviates  a little  to  the  left ; in  the  thorax  it 
proceeds  behind  the  base  of  the  heart,  and  between  the 
layers  of  the  posterior  mediastinum,  from  which  it  receives 
a covering.  On  entering  the  thorax,  it  passes  downwards 
upon  the  right  side  of  the  aorta.  It  then  perforates  the 
diaphragm,  and,  after  a very  short  course,  arrives  at  the 
stomach. 

It  is  connected  to  the  adjacent  parts  by  a loose  and  ex- 
tensile cellular  tissue,  which  contains  a number  of  lympha- 
tic glands. 

Its  outer  surface  is  smooth  in  its  whole  extent,  and  of  a 
red  color  above,  but  becoming  paler  as  it  descends  : its  in- 
ner surface  is  whiter  than  that  of  the  pharynx,  and  presents 
longitudinal  folds. 

The  oesophagus,  like  the  pharynx,  is  composed  of  a 
muscular  coat,  and  a mucous  membrane. 

The  muscular  coat  consists  of  two  strata  ; the  external  of 
which  has  thick,  strong,  longitudinal  fibres,  somewhat  fas- 
ciculated ; the  internal  is  formed  of  circular  or  transverse 
fibres,  and  is  thinner  than  the  former. 


ORGANS  OF  DIGESTION. 


189 


The  longitudinal  fibres  diverge  toward  the  stomach,  and 
may  be  traced  over  its  cardiac  extremity,  while  the  circular 
fibres  entirely  disappear  where  the  oesophagus  terminates. 

The  outer  stratum  of  fibres  is  fitted  for  shortening  and 
relaxing,  and  the  inner  for  contracting  the  canal,  during 
deglutition. 

The  mucous  membrane  is  soft,  delicate  and  white  ; it  ap- 
pears continuous  above  with  the  membrane  of  the  pharynx, 
and  is  formed  into  numerous  longitudinal  folds,  arising 
from  the  contraction  of  its  muscular  fibres. 

Between  the  muscular  and  mucous  coats  there  is  a dense 
and  compact  cellular  tissue,  to  which  the  older  anatomists 
gave  the  name  of  the  nervous  coat : it  is  merely  the  con- 
necting medium  of  the  two  former. 

The  mucous  follicles  of  the  oesophagus  are  thinly  distri- 
buted ; they  are  furnished  with  numerous  foramina,  which 
supply  a mucus  for  lubricating  the  passage  and  facilitating 
deglutition. 

The  office  of  the  oesophagus  is  to  convey  the  food  from 
the  pharynx  into  the  stomach ; for  the  aliment  does  not 
descend  into  the  stomach  by  its  own  weight,  as  we  are  able 
to  swallow  solids  or  fluids  with  the  head  more  dependent 
than  the  stomach  ; and,  indeed,  we  see  animals  feeding  in 
this  position,  namely,  with  the  head  lower  than  the  body  : 
it  is,  therefore,  from  a successive  dilatation  and  contraction 
of  the  muscular  fibres  of  the  canal,  that  the  contents  are 
urged  on  to  the  stomach. 

\ 


4 


190 


ORGANS  OF  DIGESTION. 


Fig  60. 


THE  STOMACH. 

The  stomach  (ventriculus),  Fig.  GO/  is  the  principal 
organ  of  digestion  ; it  is  a conoid,  elongated,  miisculo- 
mernbranous  reservoir : continuous  on  the  one  hand  with, 
a,  b,  the  CESophagus,  on  the  other  with,/,  the  duodenum. 
It  is  situated  beneath  the  diaphragm,  between  the  liver, 
and  the  spleen,  occupying  at  the  upper  part  of  the 


ORGANS  OF  DIGESTION. 


191 


abdomen,  the  epigastrium  and  a portion  of  the  left 
hypochondriiim.  The  stomach  is  destined  to  receive 
the  food  from  the  oesophagus,  and  afterwards  to  convert  it 
into  chyme,  before  transmitting  it  to  the  intestines. 

The  dimensions  of  this  organ  vary  according  to  the 
quantity  of  aliment  it  contains;  it  is  much  larger  in  those 
individuals  who  eat  much,  than  in  other  persons. 

The  cardiac,  or  large  extremity,  h,  is  situated  in  the  left 
hypochondriac  region,  approaches  the  spleen,  and  is  con- 
siderably higher  than  the  small  extremity. 

The  upper  surface,  g,  is  turned  towards  the  diaphragm, 
the  under,  towards  the  intestines  ; but  when  we  examine 
the  abdomen  after  death,  unless  the  stomach  is  consider- 
ably distended,  it  falls  on  the  spine,  so  that  the  superior 
surface  becomes  anterior,  and  the  inferior  surface  posterior. 

The  large  curvature,  e,  is  situated  obliquely  forwards  and 
downwards ; the  small  curvature,  d,  is  opposite  to  the  large 
one,  and  towards  the  spine. 

The  left,  or  cardiac  aperture,  of  the  stomach,  is  the  ter- 
mination of,  h,  the  oesophagus. 

The  right  aperture,  or  the  pylorus,  c,  terminates'  the 
stomach  to  the  right,  and  communicates  with,  f the  duo- 
denum : it  consists  of  a duplicature  of  the  two  inner  tunics, 
which  project  into  the  passage,  dividing  the  stomach,  and 
intestines  ; it  contains  circular  muscular  fibres,  called  the 
sphincter  pylori:  or,  I should  rather  describe  it,  as  a solid 
fibrous  ring,  interposed  between  the  peritonaeal  and  mucous 
surface  of  the  pylorus. 


THE  ORGANIZATION  OF  THE  STOMACH, 

The  stomach  is  formed  of  three  membranes,  a serous,  a 
muscular,  and  a mucous ; these  are  connected  together  by 
cellular  tissue,  and  supplied  with  vessels  and  nerves. 


192 


ORGANS  OF  DIGESTION. 


The  sej'ous  membrane  is  merely  the  peritonmal  covering; 
and,  in  this  situation,  has  a transparent,  smooth  and  white 
appearance;  it  is  externally  lubricated  by  a serous  fluid. 
It  is  united  to  the  muscular  membrane  by  a cellular  tissue. 

The  muscular  membrane,  or  tunic,  is  composed  of  pale 
fibres,  disposed  in  three  diflerent  directions.  1st.  Some  of 
these  fibres,  which  are  more  longitudinal,  are  superficial ; 
others,  which  are  extended  over  the  surface,  are  more 
irregularly  distributed.  The  2d  plane  of  fibres  lies  imme- 
diately under  the  former  ; these  fibres  are  aVeuZar,  and  run 
parallel  to  each  other.  In  the  3d  series  the  fibres  are 
oblique,  and  may  be  observed  in  broad  fasciculi  upon  the 
extremities  of  the  stomach. 

A layer  of  dense  cellular  tissue  unites  the  muscular  to 
the  mucous  tissue.  This  layer  has  been  very  improperly 
named,  by  the  old  anatomists,  the  nervous  coat. 

The  mucous  7nembrane,  or  tunic,  forms  the  inner  surface 
of  the  stomach  ; it  is  of  a pale  pink  color,  and  marbled 
appearance,  crowded  with  villosities  which  seem  to  consti- 
tute a downy  and  colored  tissue,  continually  covered  with 
an  abundant,  viscid,  inodorous  fluid.  When  the  stomach 
is  empty  this  membrane,  from  the  contraction  of  the  mus- 
cular fibres,  presents  numerous  wrinkles,  which  are  termed 
the  ruga,  of  the  stomach. 

This  surface  has  a velvet-like  appearance,  and  when  in- 
jected and  examined  with  a powerful  lens,  we  find  it  form- 
ed of  fine,  sliort,  prominent  villi,  which  are  crowded  with 
an  infinity  of  small  vessels,  whose  office  is  to  furnish  that 
particular  fluid,  called  the  gastric  juice,  which  is  the  prin- 
cipal agent  of  digestion. 

There  is  also  a number  of  orifices  on  the  mucous  mem- 
brane ; these  are  the  openings  of  the  mucous  follicles, 
which  are  distributed  in  very  regular  order. 


ORGANS  OF  DIGESTION. 


193 


OFFICE  OF  THE  STOMACH. 

It  is  the  office  of  the  stomach  to  receive  the  food  after  it 
is  prepared  by  mastication,  likewise  liquid  nutriment  or 
other  fluids,  and  to  secrete  the  gastric  juice,  and  subse- 
quently to  transmit  the  digested  mass  to  the  small  intes- 
tines. In  the  stomach,  the  food  is  converted  into  chyme  by 
the  solvent  power  of  the  gastric  fluid,  which  gradually  acts 
on  the  ingesta,  from  the  superficies  to  the  centre  of  the 
mass,  and  as  soon  as  a portion  of  it  is  reduced  to  a homo- 
geneous consistence,  it  passes  into  the  duodenum,  without 
waiting  till  the  same  change  has  pervaded  the  whole. 

The  stomach  is  amply  furnished  with  nerves  from  each 
nervous  department,  — hence,  its  great  sensibility  to  all 
kinds  of  stimuli,  and  its  disturbance  by  mental  causes,  — 
hence,  also,  the  surprising  sympathy  existing  between  it 
and  most  functions  of  the  system,  so  that  the  healthy  con- 
dition of  the  stomach  actually  depends  upon  the  tranquillity 
of  the  mind. 


THE  INTESTINAL  CANAL. 

The  intestinal  canal  extends  from  the  pylorus  to  the  anus, 
and  in  the  human  subject  varies  from  thirty  to  thirty-five 
feet  in  length.  It  is  coiled  on  itself,  so  as  to  form  folds  or 
convolutions,  and  is  divisible  into  two  parts,  differing  in 
size  and  situation,  as  well  as  external  conformation,  the  di- 
vision between  them  being  moreover  marked  by  a peculiar 
valvular  structure,  which  prevents  a reflux  of  the  ingesta 
after  they  have  passed  beyond  it.  The  part  of  the  canal 
between  the  pylorus  and  the  valve  just  referred  to,  is  called 
the  small  intestine,  the  remainder  thence  onward  to  the 
anus,  the  large  intestine. 

^5 


VOL.  II. 


194 


ORGANS  OF  DIGESTION. 


THE  SMALL  INTESTINE. 

The  term  small  intestines  is  calculated  to  give  us  a false 
idea  of  the  nature  of  the  smaller  portion  of  the  alimentary 
canal,  the  small  intestines  being  only  one  continued  cylin- 
drical tube,  but  on  account  of  the  situations  of  its  various 
parts,  or  other  circumstances  which  will  subsequently  be 
adverted  to,  it  is  convenient  to  distinguish  it  into  three 
divisions ; namely,  the  duodenum,  the  jejunum,  and  the 
ilium. 


THE  DUODENUM. 

This  portion  of  the  intestines  differs,  however,  so  mate- 
rially from  the  others,  as  scarcely  to  admit  of  the  above  ar- 
rangement ; for  it  is  not  invested  with  a serous  membrane, 
the  peritoneum  being  only  partially  applied  upon  it  in  a 
small  extent,  nor  is  it  supported  by  the  mesentery,  and  its 
volume  is  so  large,  that  it  frequently  equals  the  stomach  in 
size  ; for  this  reason,  and  others  which  will  be  presently 
noticed,  it  has  obtained  the  name  of  ventriculus  succentu- 
riatus. 

The  duodenum  is  so  named  on  account  of  its  length  be- 
ing commonly  estimated  at  twelve  fingers’  breadth  ; it  is 
that  portion  of  the  intestinal  canal,  which  immediately 
succeeds  to  the  stomach  ; it  occupies  the  middle  part  of 
the  abdomen,  where  it  is  concealed  by  the  transverse  me- 
socolon and  the  stomach. 

The  duodenum  commences  at  the  valve  of  the  pylorus, 
where  it  is  covered  in  the  greater  part  of  its  extent  by  the 
peritonmum  ; here  we  often  observe  it  tinged  yellow  by  the 
transudation  of  bile  from  the  gall  bladder.  The  intestine 
we  are  speaking  of  proceeds  horizontally  backwards,  and 


ORGANS  OF  DIGESTION. 


195 


to  the  right,  to  near  the  neck  of  the  gall  bladder ; then  de- 
scends vertically  to  the  left,  as  far  as  the  third  lumbar  ver- 
tebra, and  terminates  by  being  directed  upwards  and  for- 
wards, towards  the  extremity  of  the  mesentery,  above  the 
superior  mesenteric  vessels. 

The  duodenum,  consequently,  forms  a kind  of  semi- 
circle, having  its  convexity  to  the  left,  and  embracing  the 
pancreas  in  its  concavity. 

The  inner  surface  of  the  duodenum,  like  that  of  the 
stomach,  is  covered  by  a mucous  membrane,  upon  which 
we  may  observe  a number  of  folds,  more  or  less,  surround- 
ing the  intestine,  and  very  close  to  each 
other ; these  are  the  valvulce  conniventes. 

Fig.  61,  represents  the  inner  surface  of  a 
portion  of  the  small  intestine.  These 
valves  are  formed  by  plaitings  of  the  mu- 
cous membrane  only,  and  they  project 
three  or  four  lines  into  its  cavity. 

In  the  interior  of  the  duodenum  we  ob- 
serve a small  tubercle,  at  the  point  of 
which  are  seen  the  united  or  separate  ori- 
fices of  the  ductus  communis  choledochus 
and  the  pancreatic  ducts. 


THE  JEJUNUM  AND  ILIUM,  PROPERLY  CALLED  THE  SMALL 
INTESTINE. 

The  small  intestine  is  continuous  with  the  duodenum, 
without  any  distinct  line  of  demarcation  to  distinguish  it. 
The  small  intestine  is  the  longest  portion  of  the  digestive 
canal,  its  length  being  about  twenty-six  feet,  or  five  times 
that  of  the  whole  body.  It  forms  a number  of  curves,  of 
which  the  concavities  are  connected  with  the  mesentery, 


196 


ORGANS  OF  DIGESTION. 


while  the  convexities  are  free  and  floating,  and  folded  upon 
each  other  in  difterent  directions  a number  of  times,  form- 
ing what  are  termed  convolutions. 


Fig.  62. 


Fig.  62,  a portion  of  the  mesentery  and  small  intestine 
removed  from  the  body,  and  suspended  by,  a,  a,  two 
threads  attached  to  the  mesentery ; h,  h,  h,  the  convolu- 
tions of  the  intestine  attached  to  it ; c,  one  of  the  mesen- 
teric glands. 

The  small  intestine  commences  under  the  superior  me- 
senteric vessels,  and  terminates  in  the  coecum.  Anatomists 
usually  divided  it  into  two  portions,  although  it  is  impossi- 
ble to  assign  distinct  limits  to  each  of  them.  The  upper 
portion  is  named  the  jejunum,  from  its  being  commonly 
more  empty  than  the  other  part  of  the  intestine ; the  other 
is  called  the  ilium,  from  its  position  in  the  fossm  of  that 
name.  The  jejunum  occupies  the  upper  part  of  the  um- 
bilical region,  the  ilium  extends  as  far  as  the  hypogastric 


ORGANS  OF  DIGESTION. 


197 


and  iliac  regions.  An  examination  of  the  small  intestine, 
however,  shows  no  natural  division  of  this  kind,  so  that 
the  limits  of  the  two  portions  are  quite  arbitrary. 

Its  whole  outer  surface  is  perfectly  smooth,  and  contain- 
ed between  the  two  laminae  of  the  mesentery  ; its  inner 
surface  has  the  same  structure  and  appearance  as  the  duo- 
denum ; the  villi  of  the  small  intestine  are  larger  than 
those  of  the  stomach ; there  are  about  four  thousand  to 
the  space  of  a square  inch,  and  their  length  is  about  one- 
fourth  of  a line  : but  the  valvulae  conniventes  are  gradually 
less  conspicuous  as  they  are  examined  towards  the  coecum. 

The  muscular  membrane  is  interposed  between  the  two 
others ; its  fibres  are  pale  and  not  very  apparent ; the 
superficial  layer  is  longitudinal  and  the  deep  fibres  are 
curved  in  the  transverse  direction  of  the  intestine ; not 
passing  entirely  round  it,  but  like  the  longitudinal  are  in- 
terrupted from  space  to  space  and  seem  composed  of  shorter 
fibres,  whose  extremities  pass  between  each  other.  The 
longitudinal  fibres  shorten  the  canal,  and  the  circular  fibres 
diminish  its  calibre ; together  they  produce  an  undulating 
movement  of  the  intestine  termed  the  peristaltic  motion. 

THE  LARGE  INTESTINE.  See  Fig.  64. 

The  large,  like  the  small,  intestine  forms  one  continued 
alimentary  canal,  the  former  extending  from  the  termina- 
tion of  the  ilium  to  the  anus.  The  large  intestine,  how- 
ever, is  distinguished  not  only  by  its  size,  but  by  its  outer 
surface  presenting  irregular  enlargements  and  depressions, 
interrupted  in  three  places  by  longitudinal  bands  of  mus- 
cular fibres.  One  of  these  depressions  is  anterior ; the 
other  two  are  posterior  ; the  annexed  figure  shews  its  form 
and  its  course  better  than  any  verbal  description.  Its 
length  is  that  of  the  body,  or  about  six  feet.  Its  volume 


198 


ORGANS  OF  DIGESTION. 


is  generally  triple  that  of  the  small  intestine,  and  it  also 
differs  from  it  in  having  papillae  of  fat,  called  appendices 
pinguedinosce,  attached  externally  to  it. 

Like  the  small  intestine,  it  is  distinguished  into  three 
portions ; termed  the  ccecum,  the  colon,  and  the  rectum. 

The  ccecum  is  only  three  or  four  inches  in  length,  and 
nearly  the  same  in  diameter ; it  consists  of  that  part  of  the 
intestine  which  is  under  the  extremity  of  the  ilium.  It  is 
situated  in  the  right  iliac  region,  resting  on  the  cavity  of 
the  corresponding  os  ilium.  The  inferior  part  forms  a 
closed  sac,  the  mouth  of  which  is  directed  towards  the 
colon. 

At  the  left  extremity  of  the  ccecum  there  is  a process  of 
about  the  same  length,  and  of  the  same  nature  with  itself, 
but  the  diameter  is  not  larger  than  that  of  a writing  quill, — 
termed  the  appendix  coed  vermiformis.  It  is  hollow  in  its 
whole  extent,  and  communicates  with  the  ccecum.  It  is 
constantly  filled  with  mucus,  but  its  uses  are  entirely  un- 
known. We  must  again  recur  to  the  union  of  the  small 
intestine  with  the  large  ; at  the  opening  of  the  former  into 
the  latter  is  situated  the  ilio-coecal  valve,  or  the  valve  of  Bau- 
hin ; this,  however,  is  merely  a projecting  of  the  intestinum 
ilium  into  the  ccecum,  so  that  the  folding  of  its  extremity 
does  not  prevent  the  faeces  from  passing  downwards,  but, 
by  the  pressure  of  the  edges  against  the  sides,  and  the  con- 
traction of  its  muscular  fibres,  it  otfers  a resistance,  under 
most  circumstances,  to  a retrograde  movement  of  the  con- 
tents of  the  intestine. 


ORGANS  OF  DIGESTION. 


199 


Fig.  63. 


Fig.  63,  exhibits  the  insertion  of  the  small  into  the  large 
intestine,  the  drawing  from  which  this  was  taken  was  infla- 
ted, dried,  and  a large  opening  cut  into  it  to  show  the  valve. 

a,  the  intestinum  ilium, — 

h,  its  valvular  opening  into  the  cavity  of  the  colon. 

c,  the  caput  cceci. 

d,  the  appendix  coeci  vermiform.is. 

e,  a portion  of  the  colon. 

The  colon  forms  the  most  considerable  portion  of  the 
large  intestine  ; it  nearly  encircles  the  small  intestine,  and 
is  a continuation  of  the  coecum,  or  that  portion  of  the  in- 
testine which  is  extended  from  the  right  iliac  region  to  the 
left.  The  colon  commences  at  the  coecum,  and  terminates 
in  the  rectum. 

The  colon  ascends  in  the  right  lumbar  region,  over  the 
kidney  of  that  side,  and  is  here  termed  the  ascending  colon. 

From  the  kidney  it  proceeds  forwards,  and  crosses  the 
abdomen  in  the  epigastric  and  hypochondriac  regions,  be- 
neath the  stomach  and  above  the  small  intestine ; it  is  here 
called  the  transverse  arch  of  the  colon. 

On  the  right  side  the  arch  is  situated  under  the  liver  and 
gall  bladder,  the  latter  of  which,  after  death,  usually  stains 


200 


ORGANS  OF  DIGESTION. 


it  with  bile.  In  the  hypochondrium  it  turns  backward 
under  the  spleen,  and  descends  in  the  left  lumbar  region 
in  front  of  the  kidney,  to  which  it  is  closely  connected ; in 
this  situation  it  is  called  the  descending  colon. 

In  the  iliac  region  it  forms  a double  curve,  compared  in 
shape  to  the  greek  letter  g,  and  hence  termed  the  sigmoid 
flexure  of  the  colon.  It  is  surrounded  in  nearly  its  whole 
circumference  by  the  peritonseum,  which  fixes  it  above  and 
behind,  by  means  of  an  extended  and  loose  fold,  termed 
the  iliac  mesocolon. 

The  rectum  has  its  name  from  being  nearly  a right  line, 
extending  from  the  last  lumbar  vertebra  to  the  anus  : it  is, 
however,  accommodated  to  the  curve  of  the  sacrum.  The 
rectum  is  smaller  than  the  coecum  or  colon,  but  is  capable 
of  great  dilatation,  and  does  not  present  those  intersections 
and  muscular  bands  which  we  find  in  the  other  portions  of 
the  large  intestines.  At  the  anus  it  contracts  into  a nar- 
row orifice,  the  sides  of  which  are  compressed  into  close, 
longitudinal  folds,  by  the  sphincter  ani  and  the  two  leva- 
tores  ani. 

The  structure  of  the  large  intestine  is  the  same  as  that 
of  the  small  intestine,  but  it  is  less  muscular.  The  villi 
of  the  inner  part  are  smaller,  the  mucous  glands  or  fol- 
licles are  very  apparent,  and  there  are  no  valvulse  conni- 
ventes.  The  most  characteristic  distinction  in  the  general 
appearance  of  the  large  intestine,  is  the  intersected  and 
cellular  divisions  throughout  its  whole  extent.  These 
cells  retain  the  matter,  and  prevent  its  too  rapid  descent 
into  the  rectum,  and  thus  allow  time  for  the  lymphatic  ves- 
sels to  collect  the  fluid  from  the  digestive  canal. 


ORGANS  OF  DIGESTION. 


201 


Fig.  64j  exhibits  the  sacculated  appearance  and  course 
of  the  large  intestine. 
a,  the  caput  coli. 
h,  the  ascending  colon. 

c,  the  transverse  arch  of  the  colon. 

d,  the  descending  colon. 

e,  the  sigmoid  flexure  of  the  colon. 

f,  the  rectum, 
the  mesocolon. 


VOL.  II 


26 


202 


ORGANS  OF  DIGESTION. 


h,  the  termination  of  the  ilium. 

i,  the  appendi.Y  cceci  vermiformis. 

Tc,  k,  k,  k,  appendices  pinguedinosae. 


THE  MESENTERY. 

The  mescntenj  is  formed  by  the  peritonseum,*  which  ad- 
vances from  the  parietes  of  the  abdomen,  and  includes  the 
intestines  in  a duplicature  of  it.  The  mesentery  is  situa- 
ted in  the  middle  of  the  intestines,  commencing  at  the  last 
turn  of  the  duodenum,  and  proceeding  obliquely  down- 
wards and  towards  the  right  side,  along  the  vertebrae  of  the 
loins,  to  the  first,  second,  and  third,  of  which  it  is  chiefly 
connected. 

Its  anterior  edge  is  more  extensive  than  the  posterior,  as 
it  corresponds  to  the  convolutions  of  the  intestines  which 
are  prevented  by  it  from  being  entangled  in  the  various 
motions  of  the  body. 

That  part  which  connects  the  small  intestine  to  the  spine 
retains  the  name  of  mesentery  ; the  other,  which  belongs 
to  the  colon,  the  mesocolon ; a portion  also  which  is  con- 
tinuous with  the  latter,  and  is  connected  with  the  rectum, 
is  called  the  mesorectum. 

Tlie  offlce  of  the  mesentery  is  to  suspend,  connect,  and 
retain  the  intestinal  canal  in  its  proper  situation  ; at  the 
same  time  allowing  it  a certain  degree  of  motion  ; it  also 
furnishes  it  with  an  exterior  covering,  lodges  numerous 
glands,  and  affords  a support  to  the  vessels  and  nerves 
which  are  distributed  to  the  intestines. 


* The  peritonoeum  is  a serous  membrane  investing  the  inner  surface  of  the 
abdomen,  and  prolonged  under  the  form  of  an  envelope  over  most  of  the 
viscera  contained  in  it.  See  Article  XVI. 


ORGANS  OF  DIGESTION. 


203 


DIGESTION. 

Our  food  in  general  is  first  submitted  to  the  mechanical 
process  of  division  by  the  teeth ; and  during  its  masti- 
cation it  becomes  intimately  mixed  and  combined  with  a 
chemical  solvent,  which  prepares  it  for  the  process  it  has 
shortly  to  undergo  in  the  stomach.  This  solvent  is  the 
saliva.  The  glands  appointed  to  produce  this  fluid  seem 
to  act  in  sympathy  with  the  stomach,  being  with  it  simul- 
taneously excited  by  the  stimulus  of  the  food,  “ or  even 
(says  Dr.  Paris)  by  the  contemplation  of  a favorite  meal.” 

When  the  alliment  is  introduced  into  the  stomach,  it 
appears  to  remain  there  a short  period  before  it  undergoes 
any  change  ; but  the  solvent  energy  of  the  peculiar  fluid, 
which  has  already  been  referred  to  under  the  appellation 
of  gastric  juice,  soon  produces  that  change  upon  the  ali- 
ment called  the  digestion,  which  converts  the  food  into 

CHYME. 

The  exact  nature  of  chyme  is  not  easy  to  describe  ; but 
physiologists  agree  in  considering  it  a homogeneous  paste, 
grayish,  of  a sweetish  taste,  slightly  acid,  and  retaining 
some  of  the  properties  of  the  food.  Magendie  has  lately 
examined  the  subject  with  great  precision,  and  it  follows 
from  his  experiments,  that  there  are  as  many  species  of 
chyme  as  there  are  varieties  of  food  ; if,  at  least,  we  may 
judge  by  color,  consistence  and  sensible  qualities.  What- 
ever be  the  nature  of  the  alimentary  substance,  introduced 
into  the  stomach,  the  chyme  will  possess  the  invariable 
property  of  an  acid,  reddening  litmus  paper,  and  it  always 
has  a sharp  odor  and  taste.  As  the  parts  of  the  food  are 
digested,  that  is,  converted  into  chyme,  they  pass  out 
of  the  stomach  into  the  duodenum,  there  to  undergo  fur- 
ther changes.  In  this  process  the  pylorus  must,  as  its 
name  implies,  be  endowed  with  a peculiar  sensibility  and 


204 


ORGANS  OF  DIGESTION. 


vigilance,  by  which  it  is  enabled  to  distinguish  between  the 
crude  and  chymified  portion,  so  as  to  admit  the  latter, 
while  it  usually  opposes  the  exit  of  the  former.  Some- 
times the  pylorus  seems  so  far  to  resist  the  egress  of  the 
contents  of  the  stomach  as  to  occasion  an  inverted  action, 
and  to  expel  the  food  by  vomiting. 

If  a liquid  holding  nutritive  matter  is  taken  into  the 
stomach,  it  is  either  coagulated  by  the  gastric  fluid,  or  its 
watery  part  is  absorbed,  and  the  solid  matter  deposited  in 
the  stomach  ; in  both  cases  the  product  is  afterwards  chy- 
mified in  the  manner  already  described.  Part  of  the  liquid 
j)asses  through  the  pylorus  into  the  intestines,  to  be  ab- 
sorbed with  the  chyle,  or  to  be  rejected  with  the  feces  ; 
and  a large  portion  of  the  liquids  is  conveyed  directly  from 
the  stomach  into  the  circulation. 

Many  anatomists  have  considered  the  duodenum  as  a 
subordinate  stomach,  for,  immediately  the  chyme  has 
arrived  at  this  part  of  the  alimentary  canal,  it  becomes 
converted  into  a more  highly  animalized  product,  termed 
CHYLE,  or  the  inilk-like  fluid  which  is  imbibed  by  the 
lacteals.  Chyle  has  been  frequently  chemically  examined, 
but  it  presents  a diflerence  in  composition,  according  to 
the  nature  of  the  aliment  from  which  it  has  been  elabora- 
ted. If  the  animal  has  eaten  substances  of  a fatty  nature, 
the  chyle  will  be  found  milky  white,  a little  heavier  than 
water,  with  a strong  and  peculiar  odor,  and  a saline  and 
sensibly  alkaline  taste ; but  if  the  food  should  not  have 
contained  fat,  it  will  be  opaline  and  almost  transparent. 
Very  soon  after  chyle  is  extracted  from  the  living  animal, 
it  becomes  firm,  by  coagulation  : it  then  gradually  sepa- 
rates into  three  distinct  parts  ; the  one  solid,  which  remains 
at  the  bottom  of  the  vessel,  the  second  liquid,  and  a third 
that  forms  a very  thin  layer  at  the  surface.  The  more 
solid  part  seems  to  be  an  intermediate  substance  between 
albumen  and  fibrin,  for  it  unites  several  properties  common 


ORGANS  OF  DIGESTION. 


205 


to  both.  The  liquid  part  of  the  chyle  resembles  the  serum 
of  the  blood  ; the  other  part  which  appears  on  its  surface 
is  a fatty  substance,  which  imparts  to  the  fluid  the  appear- 
ance of  milk.  The  comparison,  however,  which  has  been 
made  between  chyle  and  milk  has  no  real  foundation  ; for 
the  former  contains  nothing  which  exactly  agrees  with  the 
constituents  of  the  latter. 

The  lacteal  vessels  which  absorb  this  fluid  have  been 
already  described  ; they  commence  in  the  very  extended 
valvular  apparatus  of  the  mucous  membrane  of  the  intes- 
tine, by  thousands  and  tens  of  thousands  of  orifices  which 
imbibe  the  chyle.* 

The  function,  consequently,  of  the  small  intestine  is  to 
separate  the  nutritious  matter  from  the  feculent,  and  to 
convey  the  latter  into  the  colon.  In  its  progress,  the  nu- 
tritive principles  of  the  aliment  having  been  absorbed  into 
the  circulation,  the  residue  is  urged  forward  by  the  action 
termed  the  peristaUic  motion  ; the  ingesta  losing,  as  it  pro- 
ceeds towards  the  coecum,  any  portion  of  the  chyle  which 
may  have  escaped  the  lacteals  in  (he  first  portion  of  the 
small  intestine.  The  remainder  of  the  contents  accu- 
mulates to  a certain  extent  in  the  colon,  and  acquires  the 
peculiar  fetor  which  distinguishes  the  feces.  In  its  pas- 
sage in  this  part  of  the  digestive  canal,  it  is  considerably 
retarded  by  the  cells  or  compartments  into  which  the  large 
intestine  is  divided.  But  the  principal  function  of  the 


* It  is  probable  that  the  mesenteric  glands  through  which  lliey  pass  pro- 
duce an  important  change  in  the  chyle  ; but  the  nature  of  tliis  change  is 
wholly  unknown  ; it  is  certain  that  these  glands  secrete  a fluid,  which  may 
be  compressed  from  them  with  the  fingers  ; hence,  some  physiologists  have 
supposed  that  they  add  a fluid  to  the  chyle  in  order  to  purify  it ; while 
others,  again,  have  contended  that  their  use  is  to  produce  a more  intimate 
union  of  the  aliments  which  compose  it.  The  chyle  is,  at  length,  poured 
into  the  thoracic  duct,  together  with  the  lymph  which  is  brought  from  all 
parts  of  the  system,  by  the  absorbent  vessels,  and  together  they  furnish  new 
materials  to  repair  the  waste  which  the  body  is  perpetually  undergoing. 


206 


ORGANS  OF  DIGESTION. 


large  intestine,  is  to  imbibe  the  remaining  fluid  in  propor- 
tion to  the  wants  of  the  system  ; another  office  obviously 
performed  by  this  portion  of  the  alimentary  canal  is  [to 
carry  out  of  the  system  the  waste,  incident  to  the  changes 
of  the  economy,  which  is  not  removed  by  the  kidneys. 
The  fecal  matter  as  it  passes  along  the  colon  gradually  be- 
comes more  solid,  and  at  length,  when  it  enters  the  rectum, 
it  forms  a mass  of  considerable  bulk,  which  distends  its 
parietes,  and  then  creates  a sensation  of  uneasiness,  which 
announces  the  necessity  for  relief. 


ART.  X. 


ORGANS  OF  RESPIRATION. 


THE  LUNGS. 

The  lungs  are  two  cellular,  or  spongy  organs,  occupying 
the  greater  part  of  the  cavity  of  the  thorax : they  are  sep- 
arated from  each  other  by  the  mediastina  and  the  heart, 
and  are  surrounded  by  membranes  which  are  named  pleurse, 
with  which  they  are  in  contact,  so  that  no  air  can  intervene 
between  them,  unless  an  opening  is  made  into  the  bag  of 
the  pleura,  when  the  lungs  would  instantly  collapse. 

\n  figure  they  are  somewhat  conical,  their  shape  corres- 
ponding exactly  with  the  cavity  of  the  thorax,  being  round- 
ed towards  the  ribs,  and  irregularly  depressed  towards  the 
mediastinum  and  heart.  In  all  instances,  the  volume  of 
the  lungs  is  in  proportion  to  the  capacity  of  the  thorax, 
and  they  are  compressed  or  dilated  according  to  the  ex- 
pansion or  contraction  of  the  parietes ; nor  (in  a healthy 
state  of  these  organs)  does  any  vacuity  exist  in  the  interior 
of  the  chest. 

The  color  of  the  lungs  is  a pale  yellowish  red,  more 
florid  in  children,  and  of  a deeper  and  purple  hue  in  age  ; 
but  the  lung  is  always  more  colored  on  the  side  on  which 
a dead  body  has  lain  ; but  this  deeper  tinge  is  owing  merely 


208 


ORGANS  OF  RESPIRATION 


to  the  blood,  from  its  own  gravity,  falling  to  the  most  de- 
pendent part  of  the  lung.  The  general  color  of  the  lungs 
is  also  interrupted  by  small  black  spots,  irregularly  dispers- 
ed on  their  surface,  and  more  or  less  numerous,  some  of 
which  are  entirely  superficial,  others  penetrate  more  or  less 
deeply  into  the  tissue  of  the  lungs.  These  spots  do  not 
appear  till  the  age  of  ten  or  twelve  years. 

The  specific  gravity  of  the  lungs  is  much  less  than  that 
of  the  other  organs  ; when  in  their  natural  state,  they  swim 
in  water,  and  this  lightness  depends  upon  a large  quantity 
of  air  penetrating  their  whole  tissue.  In  infants,  who  have 
never  breathed,  the  lungs  generally  sink  if  immersed  in 
water.  The  absolute  weight,  however,  of  the  lungs  varies 
in  difierent  individuals,  depending  on  the  greater  or  less 
quantity  of  blood  remaining  in  them  at  the  moment  of 
death. 


ORGANS  OF  RESPIRATION. 


209 


In  this  figure  (65)  the  ribs  are  sawn  through  at  the  sides, 
and  the  anterior  parietes  of  the  thorax  removed,  in  order 
to  exhibit  the  natural  situation  of  the  lunnfs. 

a,  a,  a,  the  three  lobes  of  the  right  lung. 

b,  b,  the  two  lobes  of  the  left  luno-. 

c,  the  anterior  mediastinum. 

d,  the  thyroid  gland,  situated  on  the  trachea. 

e,  the  thyroid  cartilage. 

VOL.  II.  27 


‘ilO 


ORGANS  OF  RESPIRATION. 


ORGANIZATION  OF  THE  LUNGS. 

Each  of  the  lungs  is  divided  into  sections,  called  lohes, 
varying  in  depth  in  diflerent  bodies.  The  right  lung  con- 
tains three  lobes,  the  left  two ; each  of  which  lobe  is  sub- 
divided into  lobules,  which  are  of  different  sizes  and  of 
irregular  angular  forms;  distinct  at  the  exterior,  and  sepa- 
rated from  each  other  by  whitish  grooves  of  cellular  tissue. 
Each  of  these  lobules  is  again  divided  into  air  cells,  the 
intricate  structure  and  figure  of  which  are  unknown. 

The  pulmonary  lobules,  therefore,  are  formed  of  a spongy 
tissue,  the  areola,  of  which  are  so  small  as  to  require  a 
powerful  lens  distinctly  to  observe  them : these  areolie 
communicate  with  each  other,  and  are  surrounded  by  a thin 
layer  of  cellular  tissue,  which  separates  them  from  the  ad- 
joining lobules. 

One  of  the  branches  of  the  air  tubes  (bronchi),  and  the 
pulmonary  artery,  are  distributed  to  the  lobule,  and  the  lat- 
ter then  terminates  in  the  radicles  of  the  pulmonary  veins. 
This  is  proved  by  injecting  colored  water  into  the  pulmo- 
nary artery,  when  the  injected  matter  immediately  passes 
into  the  pulmonary  veins  ; but,  at  the  same  time,  a small 
portion  enters  the  bronchi : this  circumstance  establishes 
the  fact  of  the  intimate  connection  between  the  organs  of 
respiration  and  circulation. 

The  outer  surface  is  covered  by  a glossy  serous  mem- 
brane, named  the  pleura,*  which  will  be  subsequently  de- 
scribed. 

The  lungs  are  very  elastic,  and  constantly  kept  in  a state 
of  distention  by  the  pressure  of  the  atmosphere  : this  is 
proved  by  puncturing  the  parietes  of  the  thorax,  when  they 
instantly  collapse.  During  inspiration  the  intercostal  mus- 


* See  Article  XVI. 


ORGANS  OF  RESPIRATION. 


211 


cles  raise  and  draw  out  the  ribs,  and  the  diaphragm  de- 
scends ; the  enlargement  of  the  thoracic  cavity  follows  of 
necessity  the  greater  distention  of  the  lungs,  from  the  di- 
minished resistance  to  the  air  gravitating  in  the  bronchi  and 
pulmonary  areolae.  The  diaphragm  and  muscles  of  respi- 
ration ceasing  to  act,  the  substance  of  the  lungs,  from  its 
elasticity,  recovers  its  former  dimensions,  and  e.vpels  the 
additional  volume  of  air  just  admitted,  and  the  respiratory 
muscles  follow  the  shrinking  substance  of  the  lungs,  offer- 
ing from  their  relaxation  no  resistance  to  the  atmosphere 
pressing  on  the  surface  of  the  chest  and  abdomen.  Thus 
expiration  is  produced  : thus  the  lungs  are  continually  ex- 
panding to  admit  the  atmospheric  air,  or  contracting  to 
expel  it,  from  the  hour  of  birth  to  the  latest  moment  of  our 
existence.  This  alternation  occurs  in  an  adult  at  rest  about 
twenty  times  in  a minute  — once  to  about  three  pulsations 
of  the  heart  — this  will  give  twentyeight  thousand  eight 
hundred  inspirations  in  twenlyfour  hours. 

The  mean  quantity  of  air  that  enters  the  lungs  at  each 
inspiration,  is  forty  cubic  inches  ; and  the  ordinary  quantity 
of  air  contained  in  the  lungs  is  two  hundred  and  eighty.* 
Thus,  supposing  twenty  inspirations  in  a minute,  the  quan- 
tity of  air  that  would  enter  and  pass  out  in  this  time  would 
be  eight  hundred  inches,  which  make  fortyeight  thousand 
in  the  hour,  and  in  twentyfour  hours  is  one  million  one 
hundred  and  fiftytwo  thousand  cubic  inches. 

Inspiration  and  expiration  are  intended  to  renew,  in  part, 
the  mass  of  air  contained  in  the  lungs  : it  may  be  here  re- 
marked, that  the  portion  of  air  expired,  is  not  exactly  that 
which  was  inspired  immediately  before,  but  a portion  only 
of  the  quantity  which  the  lungs  contained  after  inspiration. 

The  office  of  the  lungs  is  to  produce  certain  atmospheric 
changes  in  the  blood,  which  are  essential  for  the  support  of 
life. 


Dr.  Thomp  SON. 


212 


ORGANS  OF  RESPIRATION. 


The  air  in  its  passage  to  the  lungs,  by  passing  through 
the  mouth  or  the  nose,  the  pharynx,  the  trachea,  and  the 
bronchi,  becomes  of  a similar  temperature  with  the  body, 
and  is  cliarged  with  the  vapor  which  it  carries  from  the  air 
passages  ; and  in  this  state,  rarefied  and  humid,  it  arrives 
in  the  pulmonary  lobules,  to  mix  with  that  which  the  lungs 
contained  before. 

PHYSICAL  AND  CHKMICAL  CHANGES  WHICH  TAKE  PLACE  IN 
RESPIRATION. 

The  air,  in  its  exit  from  the  lungs,  partakes  of  the  tem- 
perature of  the  body  ; there  escapes  with  it  a great  quan- 
tity of  aqueous  vapor,  called  'pulmonary  transpiration,  and 
its  chemical  composition  is  very  different  from  the  inspired 
air. 

The  atmospheric  air  we  breathe  contains  0-21  of  oxygen, 
and  a trace  of  carbonic  acid  ; the  air  which  passes  out  of 
the  lungs  contains  0T4  or  0T5  of  oxygen,  and  0-6  to  Q'l 
of  carbonic  acid  : generally,  the  quantity  of  carbonic  acid 
is  less  than  the  quantity  of  oxygen  which  has  disappeared. 

The  quantity  of  oxygen  consumed  by  an  adult,  accord- 
ing to  Lavoisier  and  Sir  H.  Davy,  is  thirtytwo  cubic 
inches  in  a minute,  which  gives,  for  twentyfour  hours, 
fortysix  thousand  and  thirtyseven  inches. 

We  may,  therefore,  easily  calculate  the  quantity  of  car- 
bonic acid  that  passes  out  of  the  lungs  in  the  same  time, 
since  it  nearly  represents  the  volume  of  oxygen  that  has 
disappeared.  Thompson  values  it  at  forty  thousand  cubic 
inches,  though,  he  says,  it  is  probably  a little  less  : now  this 
quantity  of  carbonic  acid  represents  twelve  ounces  of  solid 
carbon. 

If  we  are  attentive  to  our  respiration,  we  shall  find  the 
degree  of  alteration  that  the  air  undergoes  in  our  lungs,  by 


ORGANS  OF  RESPIRATION. 


213 


a feeling  which  inclines  us  to  renew  it : if  the  breathing  is 
suspended  for  many  seconds,  there  is  anxiety  and  fear, 
and,  as  it  were,  an  instinctive  warning  of  the  importance  of 
respiration. 

The  changes  of  the  quality  of  the  air  during  respiration 
have  been  described,  in  which  time  the  blood  circulating 
through  the  lungs  also  undergoes  a corresponding  and  re- 
markable alteration.  That  the  oxygen  exerts  an  agency 
on  the  blood,  is  a fact  showm  by  direct  experiments  ; the 
blood,  whether  arterial  or  venous,  when  agitated  in  contact 
with  common  air,  imparts  carbon,  and  converts  the  oxygen 
into  carbonic  acid : it  is,  therefore,  a fair  inference  that,  in 
the  body,  the  change  of  inspired  oxygen  into  carbonic  acid 
is  effected  in  the  same  manner.  In  the  areolae,  or  air  cells 
of  the  lungs,  the  oxygen  may  be  considered  as  almost  in 
contact  with  the  blood  contained  in  the  ramifications  of  the 
pulmonary  vessels  ; inasmuch  as  nothing  but  the  exceed- 
ingly thin  substance  of  the  vessels  is  interposed.  When 
the  oxygen  of  the  air  is  taken  into  the  lungs,  after  a mo- 
mentary contact,  as  it  may  be  called,  with  the  blood,  it  is 
discharged  again  during  expiration  ; but  part  of  it  has  com- 
bined with  carbon.  As  it  regards  this  combination,  there 
have  been  two  opinions.  The  one  is  that  the  oxygen  of 
the  air  instantly  dissolves,  and  combines  with  the  carbon- 
aceous matter  found  in  the  blood,  and  immediately  after  is 
expired  as  carbonic  acid.  The  other  is,  that  the  oxygen  of 
the  air  is  absorbed  by  the  blood  in  the  lungs;  that  it  circu- 
lates with  the  blood  throughout  the  whole  system,  during 
which  it  combines  with  carbon  ; and  that,  on  the  return  of 
the  sanguineous  current  to  the  lungs,  the  carbonic  acid 
thus  produced  exudes  through  the  coats  of  the  minuter 
vessels,  and  is  expired.  This  latter  opinion  is  most  proba- 
ble. For  if  blood  is  merely  exposed  to  the  atmosphere  for 
the  space  of  three  minutes,  no  change  is  produced  ; but  if 
it  is  agitated  with  it  during  the  same  time,  carbonic  acid  is 


214 


ORGANS  OF  RESPIRATION. 


produced.  Independently  of  the  evidence  afforded  by  this 
experiment,  it  might  be  reasonably  expected  that  the  car- 
bon of  the  blood  would  require  more  than  an  instantaneous 
contact  with  the  oxygen  of  the  air,  before  a combination 
could  take  place.  Such  a condition  would  be  fulfilled,  if 
the  oxygen  were  to  circulate  with  the  blood  for  two  minutes 
and  a half;  for  this,  as  far  as  is  known,  is  the  space  of  time 
which  the  whole  volume  of  the  blood  requires  to  travel 
from  the  lungs  back  again  to  the  lungs;  and  this  is  the 
space  of  time  found  necessary  to  continue  the  agitation 
of  the  blood  in  the  experiment  just  named.  If  in  that 
experiment,  actual  contact  of  the  blood  with  oxygen  during 
three  minutes  did  not  evolve  any  carbonic  acid,  it  would 
be  singular  if,  in  the  lungs,  carbonic  acid  could  be  formed 
during  the  time  occupied  by  one  inspiration,  especially  as  the 
substance  of  the  blood-vessels  and  air  tubes  are  interposed. 

To  confine  the  office  of  the  lungs  to  the  mere  removal 
of  redundant  carbon  from  venous  blood,  is  to  take  a limit- 
ed view  of  its  operation,  and  to  underrate  the  utility  and 
necessity  of  the  complex  and  astonishing  mechanism  by 
which  so  simple  an  object  would  be  accomplished.  To  the 
process  of  respiration,  the  construction  of  the  chief  parts 
of  the  animal  system  are  subservient ; if  respiration  be  sus- 
pended, so  is  life : even  the  atmosphere  is  constituted  in 
such  a way  as  to  conduce  to  the  due  performance  of  this 
function.  We  know  the  important  and  extensive  agency 
of  oxygen  in  creation : can  we  doubt  in  the  laboratory  of 
the  body,  where  chemical  changes  are  incessantly  taking 
place,  that  oxygen  is  less  constantly  in  demand?  And  is 
it  not  probable  that  the  medium  of  supply  of  oxygen  to  all 
these  parts  is  that  obvious  one,  which,  in  order  to  receive  the 
supply,  is  presented  in  thousands  of  currents,  to  thousands 
of  currents  of  air,  the  absorption  being  promoted  by  the 
two  most  efficacious  means  — motion  and  extensive  surface? 

The  view  here  taken  of  the  phenomena  of  respiration 


ORGANS  OF  RESPIRATION. 


215 


corresponds  with  the  conclusions  arrived  at,  from  an  e.\- 
tended  series  of  experiments  made  by  Dr.  Edwards,*  who 
appears  to  have  established  four  fundamental  points. 

1st.  The  absorption  of  oxygen,  which  disappears. 

2d.  The  exhalation  of  carbonic  acid,  which  disappears. 

3d.  The  absorption  of  azote. 

4th.  The  exhalation  of  azote. 

The  oxygen  which  disappears  in  the  respiration  of  at- 
mospheric air  is  wholly  absorbed.  It  is  afterwards  wholly, 
or  in  part,  conveyed  into  the  circulation.  It  is  replaced  by 
exhaled  carbonic  acid,  which  proceeds  wholly,  or  in  part, 
from  that  which  is  contained  in  the  mass  of  the  blood. 

An  animal  breathing  atmospheric  air  also  absorbs  azote ; 
this  is  likewise  conveyed  wholly,  or  in  part,  into  the  mass 
of  blood. 

In  different  individuals,  it  has  been  found  that  different 
quantities  of  oxygen  is  consumed,  and  of  course  v^different 
quantities  of  carbonic  acid  returned.  The  breath  expired 
has  been  shown  to  contain  from  six  to  eight  per  cent  of 
carbonic  acid.  Drs.  Prout  and  Fyfe  have  proved  experi- 
mentally, that  particular  conditions  of  body  or  mind  render 
the  quantity  of  carbonic  acid  variable.  The  former  has 
shown  that  the  quantity  depends  also  on  the  time  of  day  : 
at  noon  it  is  at  its  maximum ; it  decreases  until  nine  at 
night ; it  then  remains  at  its  minimum  for  six  hours,  and 
at  four  in  the  morning  it  begins  to  increase.  Probably  it 
may  vary  likewise  with  the  seasons  of  the  year.  The 
above  were  the  results  obtained  in  the  month  of  August. 


THE  TRACHEA  AND  BRONCHI. 

The  trachea  is  a cylindrical  fibro-cartilaginous  and  mem- 
branous tube,  a little  flattened  posteriorly.  It  is  situated 

* On  the  Influence  of  Physical  Agents  on  Life. 


216 


ORGANS  OF  RESPIRATION. 


before  the  vertebral  column,  in  the  posterior  mediastinum', 
resting  on  the  oesophagus,  which  however,  inclines  some- 
what to  its  left  side,  and  extends  from  the  lower  part  of  the 
larynx  to  opposite  the  second  or  third  dorsal  vertebra.  It 
is  inclosed  between  the  great  vessels  of  the  neck,  and  cov- 
ered partly  by  the  thyroid  gland,  and  its  veins,  also  by  the 
sterno-hyoid  and  sterno-thyroid  muscles,  and  crossed  by 
the  vena  innominata,  the  arteria  innominata,  and  the  arch 
of  the  aorta.  At  the  second  or  third  dorsal  vertebra  it  di- 
vides into  two  lateral  branches,  termed  bronchi,  one  of 
which  passes  to  the  right  lung,  and  the  other,  which  is  the 
longest  of  the  two,  j)roceeds  under  the  arch  of  the  aorta  to 
the  left  lung. 

Each  of  the  bronchi  is  subdivided  where  it  enters  the 
lung  ; the  right  separating  into  three  principal  branches, 
corresponding  to  the  number  of  the  lobes  on  that  side  ; the 
left  into  only  two,  which  are  distributed  to  the  same  num- 
ber of  lobes  of  the  lungs  on  the  left  side.  When  the  bron- 
chi have  arrived  in  the  lungs,  they  divide  and  subdivide 
throughout  the  whole  pulmonary  tissue,  ramifying  almost 
ad  infinitum,  so  that  it  is  extremely  diflicult  to  trace  them 
to  their  termination.  Malpighi  thought  that  they  ended  in 
rounded  membranous  vesicles.  Senec  describes  the  lobu- 
les of  the  lungs  to  be  composed  of  polyhedral  vesicles,  into 
each  of  which  a twig  of  the  bronchi  enters.  If  a lung  be 
inflated  and  dried,  its  substance  when  divided,  independ- 
ently of  the  arteries  cut  through,  appears  uniformly  porous. 
Some  of  the  pores  appear  sections  of  tubes,  others  are  small 
cups,  being  sections  of  air-cells,  a hundredth  of  an  inch 
in  diameter.* 

*After  injection,  a tliin  section  of  the  lung  may  be  made,  and  submitted 
to  tlio  microscope,  when  it  will  be  found  that  the  size  of  the  areol®,  in  the 
adult,  is  nearly  as  here  stated  ; and  the  shape  of  the  areolae  appears  to  me, 
to  be,  as  stated  by  Senec,  polyhedral. 


ORGANS  OF  RESPIRATION. 


217 


THE  ORGANIZATION  OF  THE  TRACHEA  AND  BRONCHI. 

The  air  tubes  of  the  lungs  are  composed  of  fibro-cartila- 
ginous,  incomplete  rings,  membranous  mucous  follicles, 
bronchial  glands,  vessels  and  nerves. 

The  Jibro-cartilaginous  rings  in  the  tra- 
chea, Fig.  66,  are  from  sixteen  to  twenty  in 
number  ; they  are  not  complete  behind,  but 
united  by  a fibrous  membrane,  which  is 
closely  connected  with  the  oesophagus,  and 
yields  to  it  in  the  time  of  deglutition.  Each  cartilage 
forms  nearly  two  thirds  of  a circle,  as  in 
Fig.  67,  a,  a ; they  are  situated  transversely 
with  respect  to  the  length  of  the  trachea, 
and  have  their  edges  opposed  to  each  other, 
leaving  small  spaces  between  them.  These 
spaces  consist  of  the  same  fibrous  membrane 
which  completes  the  canal  at  the  posterior  part ; it  has 
great  elasticity,  so  that  when  the  lungs  are  removed  from 
the  body,  it  draws  the  fibro-cartilages  together. 

At  the  superior  part  of  the  trachea  the  cartilages  are 
sometimes  united,  but  below  they  are  perfectly  distinct 
from  each  other ; and  the  inferior  cartilage  is  triangular,  to 
adapt  itself  to  the  bifurcation  of  the  bronchi. 

In  the  bronchi,  the  primary  ramifications  are  similar  to 
those  of  the  trachea,  only  thinner  and  smaller,  and  some- 
times composed  of  several  pieces.  But  in  the  secondary 
and  ultimate  ramifications,  they  are  merely  small  irregular 
tubes,  which  gradually  diminish  until  they  arrive  at  the 
areolae  of  the  lungs. 

The  outer  membrane  is  formed  of  longitudinal  and  paral- 
lel fibres,  of  which  the  most  superficial  is  red,  the  deeper 
white.  This  membrane  alone,  posteriorly,  connects  the  car- 
tilages, and  completes  the  diameter  of  the  trachea.  Ante- 
28 


VOL.  II. 


218 


ORGANS  OF  RESPIRATION. 


riorly,  the  fibro-cartilages  appear  developed  in  its  sub- 
stance. 

Posteriorly,  this  membrane  contains  numerous  mucous 
follicles,  the  e.vcretory  ducts  of  which  open  on  its  inner  sur- 
face. They  are  named  the  glands  of  the  trachea. 

The  mucous  membrane  is  a continuation  of  the  membrane 
of  the  larynx,  and  extends  to  the  termination  of  the  bron- 
chi ; the  mucous  follicles  constantly  pour  out  a thick  fluid 
on  its  inner  surface. 

The  lymphatic  glands  of  the  bronchi,  are  situated  at  the 
bifurcation  of  the  trachea,  around  the  bronchi,  and  are 
found  even  in  the  interior  of  the  lungs.  Their  color  is 
blackish  ; they  are  easily  compressed  under  the  fingers,  to 
which  they  easily  communicate  their  color.  Their  excre- 
tory ducts  have  not  been  discovered,  and  their  functions 
also  are  unknown. 


ART.  XI. 


ORGANS  OF  THE  VOICE. 


THE  LARYNX. 


The  larynx  is  a complicated  apparatus  situated  at  the 
upper  part  of  the  trachea,  with  which  cavity  it  communi- 
cates ; it  is  immediately  under  the  os  hyoides  which  is 
placed  at  the  root  of  the  tongue.  It  is  broader  above  than 
below,  and  is  composed  of  several  cartilages,  muscles,  liga- 
ments, membranes,  and  mucous  glands. 


The  thyroid  cartilage,  Fig.  68,  is  the  largest  and  most 


THE  CARTILAGES  OF  THE  LARYNX. 


THYROID  CARTILAGE. 


prominent  of  the  pieces  com- 
posing the  larynx,  and  occupies 
its  anterior  and  lateral  parts  : 
in  its  natural  situation  it  forms 
two  lateral  wings,  or  portions 
of  a quadrangular  form,  uniting 
in  the  middle  in  a longitudinal 
angle,  which  can  readily  be 
felt  in  the  fore  part  of  the 
throat ; and  from  its  being 


b 


Fig.  C8. 


I 


220 


ORGANS  OF  THE  VOICE. 


larger  and  more  projecting  in  men  than  in  women,  has 
obtained  the  name  of  poiniim  Adanii.  The  upper  part  of 
the  angle  is  formed  into  a notch,  from  which,  and  from 
the  upper  edge  of  the  cartilage  in  general,  a broad  liga- 
ment ascends  to  unite  it  to  the  inferior  part  of  the  os 
hyoides. 

From  the  posterior  angles  we  observe  four  projecting 
processes  called  cornua,  two  of  which  a,  a,  are  termed  the 
superior  cornua,  and  are  connected  by  round  ligaments  to 
the  os  hyoides.  The  other  two,  b,  h,  are  called  the  infe- 
rior cornua  ; these  are  shorter  than  the  superior,  and  some- 
what moved  backwards,  to  be  attached  by  smooth  articu- 
lating surfaces  to  the  sides  of  the  cricoid  cartilage. 

CRICOID  CARTILAGE. 

The  cricoid  cartilage  is  placed  below  the  thyroid,  and 
like  it  can  readily  be  felt  in  the  fore  part  of  the  neck.  It 
is  narrow  anteriorly,  see  Fig.  69  ; and  thick,  broad,  and 
strong,  posteriorly,  see  Fig.  70  : its  superior  edge  has  its 


Fig.  69.  Fig.  70. 


anterior  part  fixed  to  the  thyroid  cartilage  ; the  inferior 
edge  is  connected  to  the  whole  circumference  of  the  com- 
mencement of  the  trachea. 

This  cartilage  has  four  small  articulating  surfaces,  with 
distinct  capsular  ligaments  ; two  of  which  are  situated  at 


ORGANS  OF  THE  VOICE. 


221 


its  upper  part,  for  the  articulation  of  the  arytenoid  carti- 
lages, and  two  at  the  under  part,  for  the  attachment  of  the 
inferior  cornua  of  the  thyroid  cartilage. 

ARYTENOID  CARTILAGES. 

The  arytenoid  cartilages  (Fig.  71,  the  outer,  and  Fig.  72, 
the  inner  view),  are  two  in  number  ; they  are  situated  at 


Fig.  71.  Fig.  72. 


the  upper  and  back  part  of  the  larynx,  above  the  cricoid 
cartilage.  Their  form  is  before  us  ; the  anterior  surface  is 
convex,  but  upon  each  convexity  there  is  a depression, 
which  is  occupied  by  glands.  Their  upper  extremities 
are  placed  towards  each  other : their  lower  extremities  are 
broad,  and  are  articulated  by  capsular  ligaments  with 
the  cricoid  cartilage,  upon  which  they  are  moved  by  the 
action  of  various  muscles.  They  are  also  connected  to 
each  other,  and  to  the  adjacent  cartilages,  by  ligaments  and 
muscles. 

The  aperture  between  the  arytenoid  cartilages  is  called 
the  glottis. 


222 


ORGANS  OF  THE  VOICE. 


EPIGLOTTIS. 


The  epiglottis  (Fig.  73,  the  outer,  and  Fig.  74,  the  inner 
view),  has  obtained  its  name  from  its  situation  above  the 


glottis  : it  is  a fibro-cartilage,  situated  at  the  upper  part 
of  the  larynx,  behind  the  base  of  the  tongue ; its  form  is 
ovoid,  its  color  a pale  yellow,  and  its  tissue  very  elastic. 
It  is  placed  obliquely  over  the  glottis,  and  may  be  seen 
and  examined  in  the  living  body  by  pressing  down  the 
tongue. 

This  cartilage  is  attached  by  a broad  and  short  liga- 
ment to  the  notch  of  the  thyroid  cartilage  ; laterally  it  is 
united  to  the  arytenoid  cartilages,  forming  at  this  part  the 
superior  opening  of  the  larynx.  It  is  united  to  the  os 
hyoides  and  tongue  by  a ligament  which  is  termed  the 
frcenum  epiglottidis . 

The  surface  is  covered  by  a number  of  small  perforations 
and  depressions,  which  contain  mucous  follicles,  or  transmit 
nervous  filaments. 


Fig.  73. 


Fig. 71. 


ORGANS  OF  THE  VOICE. 


223 


THE  LIGAMENTS  OF  THE  LARYNX. 

The  thyro-hyoid  articulation.  The  thyroid  cartilage  is 
connected  at  its  upper  part  with  the  os  hyoides  by  a broad 
yellowish  membrane.  The  superior  cornua  of  this  cartilage 
is  connected  to  the  extremities  of  that  bone  by  two  round, 
fibrous  cords,  about  an  inch  in  length. 

The  crico-thyroid  articulation.  The  thyroid  cartilage, 
in  the  middle  and  anteriorly,  is  connected  with  the  cricoid, 
by  the  crico-thyroid  ruemhrane,  and  on  the  sides,  the  infe- 
rior cornua  of  the  thyroid  cartilage  are  articulated  with  the 
cricoid  cartilage,  by  means  of  a loose  and  humid  synovial 
membrane.  There  are  also  two  ligaments  extending  from 
the  inferior  cornua  of  the  thyroid  cartilage  to  the  arytenoid 
cartilages  where  they  are  expanded. 

The  crico-arytenoid  articulation.  Each  arytenoid  car- 
tilage is  articulated  with  the  cricoid,  by  a synovial  cap- 
sule, which  is  strengthened  by  fasciculi  of  ligamentous 
fibres. 

The  vocal  ligaments,  or  the  thyro-arytenoid  articulation. 
On  the  inside  of  the  larynx  we  observe  two  ligaments. 
Fig.  75,  a,  about  two  lines  in 
breadth,  formed  of  elastic  and 
parallel  fibres,  contained  in  a 
fold  of  the  mucous  membrane  ; 
they  are  extended  horizontally 
from  the  anterior  prominence  of 
the  arytenoid  cartilage,  to  the 
centre  of  the  retiring  angle  of 
the  thyroid  cartilage.  They  are 
named  the  vocal  cords. 


Fig.  75. 


224 


ORGANS  OF  THE  VOICE. 


THE  MUSCLES  OF  THE  LARYNX. 


CRICO-THYROIDEUS 


This  muscle,  Fig.  76,  a,  a,  is  situated  on  the  side  and 
at  the  anterior  and  inferior  part  of  the  larynx ; it  ex- 


tends from  the  lateral  and  anterior  edge  of  the  cricoid 
cartilage,  to  the  lateral  and  inferior  edge  of  the  thyroid 
cartilage. 

The  office  of  this  muscle  is  to  depress  and  draw  for- 
ward the  thyroid  cartilage,  or  to  raise  the  cricoid  car- 
tilage. 


Fig.  76. 


ORGANS  OF  THE  VOICE. 


225 


CRICO-ARYTENOIDEUS  POSTICUS. 

This  muscle,  Fig.  77,  b,  is  extended  from  the  back  part 


Fig.  77. 


of  the  base  of  the  arytenoid  cartilage,  to  the  posterior  part 
of  the  cricoid  cartilage. 

Its  office  is  to  draw  back  the  arytenoid  cartilage. 


T 


VOL.  II. 


29 


226 


ORGANS  OF  THE  VOICE. 


CRICO-ARYTENOIDEUS  LATERALIS 


This  muscle,  Fig.  78,  c,  is  extended  from  the  lateral  and 


inferior  part  of  the  arytenoid  cartilage,  to  the  lateral  part 
of  the  cricoid  cartilage. 

Its  office  is  to  separate  the  arytenoid  cartilages,  and  with 
them  the  glottis. 


This  muscle,  e,  extends  from  the  fore  part  of  the  aryte- 
noid cartilage  to  the  inferior  and  posterior  part  of  the  thy- 
roid cartilage. 

Its  office  is  to  draw  the  arytenoid  cartilage  outwards  and 
forw'ards,  and  thereby  to  enlarge  the  glottis,  and  to  shorten 
and  relax  the  vocal  cords. 

A small  fasciculus  of  this  muscle,  on  its  upper  part,  is 
called  by  Albinus  thijro-arytenoideus  alter  minor. 


Fig.  78. 


THYRO-ARYTENOIDEUS 


ORGANS  OF  THE  VOICE. 


227 


ARYTENOIDEXJS. 

This  is  a single  muscle,  Fig.  77,/,  situated  at  the  supe- 
rior and  posterior  part  of  the  larynx  ; it  is  formed  of  several 
planes  of  fibres,  which  have  occasioned  it  to  be  divided  by 
many  anatomists  into  several  distinct  muscles.  It  is  at- 
tached to  the  posterior  part  of  each  of  the  arytenoid  carti- 
lages, from  whence  the  fibres  take  different  directions ; 
some  extend  from  the  base  of  the  right  cartilage  to  the 
summit  of  the  left,  others  take  an  inverse  course,  and  some 
pass  horizontally  from  the  middle  part  of  one  to  the  same 
point  of  the  other. 

The  office  of  this  muscle  is  to  close  the  glottis,  by  draw- 
ing the  arytenoid  cartilages  together ; at  the  same  time 
they  bring  the  vocal  cords  in  nearer  apposition. 


MUCOUS  MEMBRANE  OF  THE  LARYNX. 

This  membrane  is  continuous  superiorly  with  the  mucous 
membrane  of  the  mouth  ; inferiorly,  with  that  of  the  tra- 
chea and  bronchial  tubes ; posteriorly,  with  that  of  the 
pharynx.  Its  tissue  is  very  firm,  but  yet  highly  vascular,, 
and  it  contains  in  its  substance  a number  of  mucous  folli- 
cles, the  orifices  of  which  are  easily  perceived.  It  secretes 
a somewhat  tenacious  fluid,  which  keeps  its  inner  surface 
in  a moist  state. 


THE  GLAND  OF  THE  EPIGLOTTIS. 

This  gland  consists  of  small  granulations,  deeply  im- 
mersed in  a quantity  of  adipose  cellular  tissue,  and  occu- 
pying a triangular  space  at  the  lower  part  of  the  anterior 


228 


ORGANS  OF  THE  VOICE. 


surface  of  the  epiglottis.  It  pours  its  secretion  upon  the 
laryngeal  surface  of  the  epiglottis. 


THE  ARYTENOID  GLANDS. 

These  glands  are  situated  in  the  folds  which  the  mucous 
membrane  presents  in  passing  from  the  epiglottis  to  the 
arytenoid  cartilages,  and  from  these  to  the  thyroid  cartilage. 
Tliey  are  composed  of  small  granulations  resembling  those 
of  the  lachrymal  gland. 

There  is  much  difficulty  in  discovering  their  excretory 
orifices. 


THE  OFFICE  OF  THE  LARYNX. 

All  the  modifications  of  the  voice  are  produced  by  the 
air  passing  from  the  lungs  through  the  larynx  ; sounds  may 
also  be  produced  by  it  in  the  time  that  air  traverses  the 
larynx  to  pass  into  the  trachea,  but  these  tones  are  pro- 
duced with  more  difficulty,  and  are  not  according  to  the 
ordinary  laws  of  economy.  If  we  blow  air  into  the  trachea 
towards  the  larynx,  at  the  same  time  bringing  the  arytenoid 
cartilages  together,  a sound  will  be  produced  something 
like  the  voice  of  the  animal,  to  which  the  larynx  used  in 
the  experiment  belongs. 

The  sound  will  be  dull  or  sharp  according  as  the  carti- 
lages are  pressed,  more  or  less  forcibly,  together,  and  its 
intensity  will  be  according  to  the  force  of  the  current  of 
the  air.  We  may  observe,  in  this  experiment,  that  the 
sound  is  produced  by  the  vibrations  of  the  vocal  cords. 

The  strength  of  the  voice  depends  upon  the  extent  of 
the  vibrations  of  the  vocal  cords,  and  these  will  be  in  pro- 
portion to  the  force  with  which  the  air  is  expelled  from  the 


ORGANS  OF  THE  VOICE. 


229 


chest.  The  tone  of  the  voice  generally  agrees  with  the 
state  of  the  cartilages  of  the  larynx. 

We  can,  therefore,  account  for  the  production  of  voice 
on  physical  principles.  I will  transcribe  the  explanation 
given  by  Magendik.  “ The  air  being  pressed  from  the 
lungs,  proceeds  in  a pipe  of  considerable  size  ; this  pipe 
very  soon  becomes  contracted,  and  the  air  is  forced  to  pass 
through  a very  narrow  slit,  the  two  sides  of  which  are 
vibrating  plates,  which  permit  and  intercept  the  air,  like 
the  plates  of  reeds,  and  in  the  same  manner,  by  these  alter- 
nations, produce  sonorous  undulations  in  the  transmitted 
current  of  air.” 


THE  THYROID  GLAND. 

This  body.  Fig.  79,  covers 
the  lower  and  anterior  part  of 
the  larynx,  and  the  first  two 
or  three  cartilages  of  the  tra- 
chea: it  is  composed  of  two 
lobes,  generally  united  in  a 
great  part  of  their  extent;  but 
frequently  they  are  unconnected,  except  by  a sort  of 
transverse  cord. 

The  structure  of  the  thyroid  body  is  soft  and  spongy  ; 
most  commonly  it  is  of  a brownish  red  color,  and  is  com- 
posed of  a number  of  distinct  lobules.  An  oily  or  a milky 
fluid  may  be  pressed  from  its  areolae,  but  it  is  an  organ  re- 
specting the  office  of  which  we  are  totally  ignorant,  and 
which  anatomists  usually  describe  after  the  larynx,  merely 
on  account  of  its  situation. 


Fig.  79. 


ART.  XII. 


ORGANS  OF  SECRETION. 


ORGANS  FOR  THE  SECRETION  AND  TRANSMISSION  OF  THE 

TEARS. 

These  organs  consist  of  the  lachrymal  glands,  the  puncta 
lachrynialia,  the  lachrymal  ducts,  the  caruncula,  the  lachry- 
mal sacs,  and  the  nasal  canals. 

THE  LACHRYMAL  GLAND. 

This  gland,  Fig.  80,  a, 
is  situated  in  a depression 
of  the  frontal  bone,  at  the 
upper,  outer  and  fore  part 
of  tlie  orbit.  It  is  about 
the  size  of  a small  al- 
mond, but  the  form  is 
various,  most  commonly 
it  is  a flattened  ovoid. 

Its  color  is  light  yellow, 
inclining  to  red. 

The  lachrymal  gland  is 
formed  of  a considerable 


Fig.  80. 


/> 


ORGANS  OF  SECRETION. 


231 


number  of  lobules,  connected  by  cellular  tissue,  and  these 
lobules  are  composed  of  granulations,  the  intimate  struc- 
ture of  which  is  still  entirely  unknown.  It  is  supposed 
that  from  each  of  them  issues  a small  excretory  tube,  which 
unites  with  others  in  its  vicinity,  and  forms  trunks  more 
distinct.  It  appears  that  there  are  six  or  seven  in  number, 
h,  and  that  they  open  on  the  inner  surface  of  the  eyelid. 

A fibro-cellular  capsule  of  considerable  thickness  en- 
velopes the  lachrymal  gland. 


THE  CARUNCULA  LACHRYMALIS. 

The  caruncula  lachrymalis,  e,  is  a small  red  tubercle,  sit- 
uated in  the  inner  angle  of  the  eyelids : it  consists  of  a 
mass  of  mucous  crypts  or  follicles,  covered  by  the  con- 
junctiva, and  forming,  on  its  outer  side,  a fold*  which  al- 
lows of  the  motion  of  the  globe  of  the  eye.  Each  orifice 
of  the  crypts  is  furnished  with  hairs  of  excessive  delicacy, 
and  visible  only  with  a lens. 


THE  PUNCTA  LACHRYMALIA. 

The  puncta  lachrymalia  are  two  in  number,  one  for  each 
eyelid  ; they  occupy  the  centre  of  a small  tubercle  at  c,  c, 
these  are  the  orifices  of  the  lachrymal  ducts,  which  convey 
the  tears  into,/,  the  lachrymal  sac. 

* This  folding  of  the  conjunctiva  is  termed  by  anatomical  writers,  the 
remains  of  the  membrana  nictitans : such  a name,  however,  is  quite  absurd, 
as  it  has  no  such  office,  structure,  or  muscular  apparatus,  as  that  membrane. 
The  use  of  this  fold  is  simply  to  permit  of  the  turning  of  the  eye  outwards  : 
for  that  purpose  there  is  a similar  lax  fold  at  the  opposite  angle,  and  at  the 
connexion  of  the  superior  and  the  inferior  palpebrse  with  the  globe  of  the 
eye.  If  these  foldings  of  the  conjunctiva  did  not  exist,  the  eye  would  be 
fixed,  and  it  would  be  impossible  that  the  eye  could  be  revolved  in  an}' 
direction. 


232 


ORGANS  OF  SECRETION. 


THE  LACHKYMAL  SAC. 

The  lachrymal  sac,  f,  is  a small  membranous  bag,  situa- 
ted in  a groove  of  the  os  unguis,  and  ascending  process  of 
the  upper  maxillary  bone.  It  receives  the  lachrymal  ducts, 
and  is  continued  into  the  nasal  duct. 


THE  NASAL  DUCT. 

This  canal,  g,  is  continued  from  the  lachrymal  sac,  and 
opens,  at  h,  into  the  nasal  fossa,  beneath  the  inferior  turbi- 
nated bone,  by  an  orifice  provided  with  a circular  fold  o 
the  pituitary  membrane.  This  canal  is  lined  by  a continu- 
ation of  the  mucous  membrane  of  the  lachrymal  sac. 

The  nasal  duct  conveys  the  tears  into  the  nose,  which 
the  puncta  lachrymalia  have  absorbed. 

THE  SALIVARY  GLANDS. 

There  are  three  salivary  glands  situated  behind  and  be- 
low the  lower  jaw.  They  do  not  receive  vessels  at  a de- 
terminate point,  but.  are  penetrated  on  all  sides  by  adjacent 
vessels  which  ramify  in  their  texture.  They  are  surround- 
ed by  a layer  of  cellular  tissue,  and  have  excretory  ducts 
which  open  into  the  mouth. 


ORGANS  OF  SECRETION. 


233 


Fig.  81. 


1.  THE  PAROTID  GLAND. 

The  parotid  gland,  Fig.  81,  a,  is  situated  in  the  recess 
which  exists  on  the  side  of  the  face,  between  the  posterior 
border  of  the  lower  jaw  and  the  ear,  and  extends  from  the 
zygomatic  arch  as  far  as  the  angle  of  the  inferior  maxilla. 

This  gland  is  of  a grayish  white  color,  and  is  composed  of 
granulations  united  into  lobules  and  lobes  by  condensed  cel- 
lular tissue.  These  granulations  give  origin  to  excretory 
ducts,  which,  uniting,  form  h,  the  duct  of  Steno,  which 
proceeds  over  the  masseter  muscle,  and,  perforating  the 
buccinator  muscle,  opens  into  the  mouth,  on  a level  with 

VOL.  II.  30 


234 


ORGANS  OF  SECRETION. 


the  second  superior  molar  tooth.*  The  duct  is  formed  of 
two  membranes ; one  exterior,  white,  thick  and  resistant ; 
the  other  interior,  a mucous  membrane. 

We  find  in  the  substance  of  the  parotid  gland  a great 
number  of  branches  of  the  facial  nerve,  the  transverse  ar- 
tery of  the  face,  the  posterior  auricular  artery,  and  the  vein 
which  forms  a communication  between  the  external  and  the 
internal  jugular  vein. 

2.  THE  SUBMAXILL.\RY  GLAND. 

This  gland.  Fig.  81,  c,  is  situated  on  the  inner  side  of  the 
ramus  of  the  lower  jaw,  between  the  two  portions  of  the 
digastric  muscle.  Its  structure  is  similar  to  that  of  the 
parotid. 

Its  excretory  duct  is  commonly  named  Wharton’s  duct ; 
it  is  much  smaller  than  the  parotid  duct,  and  commences 
by  minute  roots  in  the  granular  substance  of  the  gland, 
passes  horizontally  between  the  genio-glossus  and  the  sub- 
lingual gland,  until  it  reaches  the  side  of  the  fraenum  of  the 
tongue,  where  it  opens  by  a narrow  orifice  placed  on  the 
centre  of  a small  tubercle. 


3.  THE  SUBLINGUAL  GLAND. 

This  gland  is  situated  under  the  fore  part  of  the  tongue  ; 
it  is  smaller  than  the  submaxillary  gland,  and  nearly  of  the 
shape  of  an  almond  ; it  is  covered  by  the  mucous  mem- 
brane of  the  mouth,  beneath  which  it  forms  a prominence. 
It  has  several  very  slender  excretory  ducts : six  or 
eight  proceed  from  its  upper  part  to  open  upon  the  sides 

*Tlie  duct  of  the  parotid  may  be  exposed  by  cutting  in  the  direction  of  a 
line  drawn  from  the  lobe  of  the  ear  to  the  anterior  openings  of  the  nares. 


ORGANS  OF  SECRETION. 


235 


of  the  fraenum  linguale,  while  five  or  six  others  issue  from 
the  lateral  parts,  and  perforate  singly  the  mucous  mem- 
brane of  the  inferior  part  of  the  mouth.  Two  or  three  of 
these  may  be  seen  terminating  in  the  submaxillary  duct. 

The  organization  is  similar  to  the  other  salivary  glands. 

The  saliva  which  these  glands  secrete  flows  constantly 
into  the  mouth,  and  mixes  with  the  fluids  produced  by  the 
membranes  and  mucous  follicles.  This  liquid  has  been 
analyzed  by  Berzelius,  and  found  to  contain  : water  93-9  ; 
a particular  animal  matter  2'9  ; mucus  1-4  ; muriate  of  soda 
and  potass  0-7  ; tartarite  of  soda  and  animal  matter  0-9  ; 
soda  0-2.  The  composition  of  the  saliva  is  known  to  be 
variable,  for  in  some  instances  it  is  sensibly  acid. 

The  saliva  is  one  of  the  most  useful  digestive  fluids  ; it 
is  favorable  to  mastication  and  division  of  the  food ; it  as- 
sists in  deglutition,  and  the  conversion  of  the  aliment 
into  chyme  ; it  also  renders  more  easy  the  motion  of  the 
tongue  in  speech  and  in  singing.  The  greatest  portion  of 
the  fluid  is  carried  into  the  stomach  by  the  motion  of  de- 
glutition ; another  portion  must  evaporate  and  go  out  of 
the  mouth  with  the  expired  air. 

THE  PANCREAS. 

The  pancreas,  Fig.  82,  is  a gland  situated  transversely 
in  the  abdomen,  behind  the  stomach.  Its  form  is  irregular 


Fig.  82. 


236 


ORGANS  OF  SECRETION. 


and  very  variable ; its  weight  is  from  three  to  six  ounces. 
Its  anterior  surface  is  covered  by  the  transverse  meso- 
colon, the  stomach,  and  the  first  portion  of  the  duodenum. 
lis  jJosterior  surface  presents,  at  its  upper  part,  a groove 
which  contains  the  splenic  vessels.  There  is  very  frequent- 
ly beneath  it  a small  detached  glandular  mass,  of  the 
same  structure,  named  the  small  pancreas. 

The  pancreas  bears  an  exact  resemblance  to  the  salivary 
glands  in  its  structure  : its  color  is  light  red,  and  from  its 
lobules  we  can  trace  the  radicles  of  its  excretory  duct, 
which,  progressively  increasing  in  size,  proceeds  in  a ser- 
pentine form  towards  the  duodenum,  where  it  is  as  large 
as  a crow-quill.  Near  its  termination  it  receives  the  ex- 
cretory duct  from  the  small  pancreas,  and  after  a short  pas- 
sage, the  common  pancreatic  duct  opens  into  the  ductus 
communis  choledochus  ; or  rather  adheres  to  it  as  it  enters 
the  duodenum  at  the  same  point. 

The  pancreatic  fluid,  I believe,  has  never  been  collected 
in  sufficient  quantity  to  be  analyzed  ; but  it  is  generally  con- 
sidered to  be  analagous  to  saliva.  Its  office,  therefore,  is 
merely  conjectural  ; and  it  is  only  known  that  this  fluid 
mingles  with  the  bile  and  is  poured  into  the  duodenum. 

ORGANS  FOR  THE  SECRETION  AND  TRANSMISSION  OF 
THE  BILE. 

THE  LIVER. 

The  liver  is  the  largest  of  all  the  glands  ; it  entirely 
occupies  the  right  hypochondriurn,  and  that  part  of  the 
epigastric  region  which  is  beneath  the  diaphragm  and 
above  the  stomach,  the  lesser  omentum,  the  duodenum, 
the  arch  of  the  colon,  the  gall  bladder,  and  the  right 
kidney  ; it  is  placed  in  front  of  the  aorta  and  inferior  vena 


ORGANS  OF  SECRETION. 


237 


cava,  and  behind  the  anterior  parietes  of  the  abdomen.  It 
is  very  dense,  its  weight,  in  the  adult,  varying  from  two  to 
five  pounds.  It  is  convex  on  the  superior  surface  and 
irregularly  concave  on  the  inferior  surface.  It  is  divided 
into  three  lobes. 

1.  The  grea^  lohe  is  situated  obliquely  in  the  right  hypo- 
chondriac region  ; it  corresponds  with  the  curve  of  the  di- 
aphragm, and  rests  upon  the  pylorus,  colon,  and  superior 
extremity  of  the  right  kidney. 

2.  The  small  lobe  is  partially  separated  from  the  greater 
by  a broad  ligament,  and  is  situated  almost  horizontally  in 
the  epigastric  region  ; only  a small  part  extending  to  the 
left  hypochondriac  region. 

3.  The  lobulus  spigelii  is  situated  on  the  left  side  of 
the  great  lobe,  and  is  of  a pyramidal  form,  projecting  be- 
tween the  cardia  and  vena  cava,  at  the  small  curvature  of 
the  stomach.  Two  prolongations*  appear  to  connect  its 
base  to  the  great  lobe  of  the  liver ; one  of  these  gradually 
loses  itself  at  its  surface  ; the  other  ascends  posteriorly  to- 
wards the  groove  of  the  inferior  vena  cava,  and  contributes 
to  its  formation. 

The  liver  has  several  depressions  and  fissures,  namely  : 

The  Jissura  umbilicalis,  or  the  groove  of  the  umbilical 
vein,  situated  between  the  large  and  small  lobes,  at  the 
under  and  fore  part  of  the  liver,  which,  in  the  foetus,  con- 
tains the  umbilical  vein  ; and  in  the  adult  it  is  occupied  by 
the  fibrous  cords  which  are  formed  by  the  remains  of  these 
obliterated  vessels. 

The  sinus  port  arum,  or  groove  of  the  inferior  vena  cava, 
is  situated  behind,  near  the  convex  edge  of  the  liver : it  is 
short  but  deep,  and  often  exists  as  a true  canal.  The  porta 
receives  the  great  blood  vessels,  and  the  nerves  which  pass 

■**  These  parts  of  the  liver  are  frequently  described  as  the  lohuhis  candatus, 
and  the  lobulus  anonymus,  or  qwidratus. 


238 


ORGANS  OF  SECRETION. 


into  the  liver,  and  the  biliary  ducts  and  absorbents  which 
proceed  from  it. 

LIGAMENTS  OF  THE  LIVER. 

The  liver  is  retained  in  its  position  by  folds  of  the  peri- 
tonaeum, termed  the  ligaments:  — 

1.  The  ligamentum  latum,  which  is  united  to  the  dia- 
phragm and  the  tip  of  the  ensiform  cartilage,  and  then  de- 
scends in  an  oblique  direction,  adhering  to  the  inner  edge 
of  the  vagina  of  the  rectus  abdominis  of  the  right  side  as 
far  as  the  umbilicus. 

2.  The  ligamentum  rotundurn,  w'hich  was  the  umbilical 
vein  in  the  foetus,  is  placed  in  a duplicature  of  the  ligamen- 
tum latum,  and  united  to  the  umbilicus. 

3.  The  ligamentum  coronarium,  unites  the  root  or  poste- 
rior part  of  the  liver  to  the  tendinous  portion  of  the  dia- 
phragm. 

4.  The  ligamentum  dextrum,  or  right  lateral  ligament, 
connects  the  posterior  part  of  the  great  lobe  of  the  liver  to 
the  diaphragm. 

5.  The  ligamentum  sinistrum,  or  left  lateral  ligament, 
connects  the  small  lobe  to  the  diaphragm.  The  two 
lateral  ligaments  are  merely  the  extension  of  the  coronary 
ligament. 

Haller  has  described  two  other  ligaments,  the  one 
connecting  the  gall  bladder  and  the  contiguous  sinus  por- 
tarum  to  the  colon,  called  the  hepato-colic  ligament;  the 
other  termed  the  hepato-renal,  which  unites  the  liver  to  the 
kidney. 


ORGANS  OF  SECRETION. 


239 


ENVELOPES  OF  THE  LIVER. 

The  peritoneal  envelope  is  reflected  from  the  lower  sur- 
face of  the  diaphragm  over  the  liver,  and  gives  it  externally 
its  shining  appearance. 

The  cellular  envelope  covers  all  the  parts  of  the  liver, 
and  is  extended  into  its  substance,  forming  sheaths  which 
accompany  the  branches  and  twigs  of  the  vena  port®,  the 
hepatic  artery,  and  hepatic  duct.  These  sheaths  have  been 
designated  the  capsule  of  Glisson. 

The  interior  substance  of  the  liver  is  of  a reddish  brown, 
or  yellowish  color.  Its  general  aspect  is  porous  ; this,  how- 
ever, arises  from  the  great  number  of  small  vessels  which 
are  divided  in  cutting  it.  If  the  tissue  of  the  liver  is  torn 
instead  of  being  cut,  it  then  appears  composed  of  an  im- 
mense quantity  of  granulations,  in  which  the  extreme  ram- 
ifications of  the  blood  vessels  and  biliary  ducts  terminate. 
The  most  minute  researches  have  disclosed  nothing  further 
with  respect  to  its  intimate  structure. 

THE  HEPATIC  DUCT. 

The  hepatic  duct  commences  by  a great  number  of  very 
slender  radicles  in  the  granulations  of  the  liver ; these 
radicles,  termed  pori  hiliarii,  unite  successively  into 
branches,  accompanied  by  the  divisions  of  the  vena  portae 
and  hepatic  artery,  and  form  two  principal  trunks,  one  from 
the  left  lobe,  the  other  from  the  right ; these  proceed  out- 
wards, and,  uniting  at  a right  angle,  form  the  hepatic  duct. 
This  duct  is  about  an  inch  and  a half  in  length,  and  a line 
and  a half  in  diameter  ; it  ascends  between  the  two  folds 
of  the  gastro-hepatic  omentum,  before  the  vena  portae,  on 
the  left  of  the  neck  of  the  gall  bladder,  and  unites  with 
the  cystic  duct. 


240 


ORGANS  OF  SECRETION. 


THE  GALL  BLADDER. 

The  gall  bladder  is  a membranous  reservoir,  situated  in 
a superficial  depression  of  the  inferior  surface  of  the  right 
lobe  of  the  liver.  It  is  composed  of  three  membranes. 
1st.  A serous  membrane,  which  is  the  peritonaeal  covering 
on  the  lower  surface.  2d.  A cellular  membrane,  which 
unites  the  serous  to  the  inner  membrane.  3d.  A mucous 
membrane  of  considerable  thickness,  which  lines  the  interi- 
or, and  has  a peculiar  honey-comb  appearance.  At  the 
neck  of  the  gall  bladder  this  membrane  forms  several  folds, 
which,  from  their  arrangement,  have  been  called  the  spiral 
valve. 


CYSTIC  DUCT. 

This  duct,  which  is  situated  in  the  gastro-hepatic  omen- 
tum, forms  a continuation  with  the  neck  of  the  gall  blad- 
der, of  about  one  inch  and  a half  in  length  ; it  is  in  appo- 
sition with  the  hepatic  duct  for  a short  distance,  and  after- 
wards unites  with  it,  forming  the  ductus  communis  choledo- 
chus,  or  the  common  canal  for  the  transit  of  the  bile. 

THE  DUCTUS  COMMUNIS  CHOLEDOCHUS. 

This  duct  is  formed  by  the  junction  of  the  cystic  and 
hepatic.  It  is  from  three  to  four  inches  in  length,  and  is 
situated  between  the  two  folds  of  the  gastro-hepatic  omen- 
tum. It  opens  with  the  pancreatic  duct  obliquely,  into  the 
duodenum  near  its  last  curve. 


ORGANS  OF  SECRETION. 


241 


Fig.  83. 


Fig.  83,  a,  the  gall  bladder,  b,  the  cystic  duct,  c,  the 
principal  branches  of,  d,  the  hepatic  duct  ; these  unite 
and  form,  e,  the  ductus  communis  choledochus,  which 
terminates  at,  A,  by  an  aperture  in  the  inner  surface  of  the 
duodenum. 


SECRETION  OF  BILE. 

The  circulation  in  the  liver  is  very  remarkable,  from  its 
receiving  blood  from  two  sources  ; the  hepatic  arteries, 
and  from  the  department  of  veins  continued  from  the  vena 
portae,  which  are  distributed  after  the  manner  of  an  artery 
throughout  the  substance  of  the  liver.  There  is  another 
department  of  veins  for  returning  the  blood,  consisting  of 
the  venae  cavae  hepaticae,  which  open  into  the  inferior  cava. 
Fluids  injected  into  the  hepatic  artery,  or  into  the  vena 
portae,  readily  pass  into  the  venae  cavm  hepaticae,  and 
into  the  hepatic  ducts.  We  may  infer  from  this  that 
VOL.  II.  31 


242 


ORGANS  OF  SECRETION. 


both  venous  and  arterial  blood  may  serve  for  the  secretion 
of  bile. 

The  bile  appears  to  be  the  most  complex  of  all  the  ani- 
mal fluids.  Professor  Mayo  states  that,  besides  a number 
of  saline  ingredients,  it  contains  mucus,  albumen,  osma- 
zome,  gliadine,  casein,  picromeJ,  asparagm,  acetic  acid, 
oleic  acid,  margaric  acid,  cholic  acid,  resin  and  coloring 
matter. 

The  bile  contributes  very  essentially  in  the  digestive  and 
assimulative  processes,  but  in  what  manner  is  unknown. 
Persons  commonly  attribute  noxious  properties  to  the  bile, 
which  it  is  probably  far  from  possessing. 

THE  SPLEEN. 

The  spleen  is  situated  in 
the  posterior  part  of  the  left 
hypochondrium,  beneath  the 
diaphragm,  behind  the  de- 
scending colon,  and  imme- 
diately over  the  left  kidney. 

Fig.  84,  shows  its  form  ; 
its  weight  cannot  be  pre- 
cisely stated,  as  it  presents 
the  most  numerous  varia- 
tions. 

It  is  attached  to  the  sur- 
rounding organs  in  a loose 
manner  by  folds  of  the  pe- 
ritonseum,  and  by  a great  number  of  vessels. 

The  spleen  is  single,  but  I have  several  times  found  a 
supernumerary  spleen  adjacent  to  it. 

The  outer  surface  is  convex  ; the  inner  is  divided  by  a 


Pig.  84. 


ORGANS  OF  SECRETION. 


243 


groove  called  the  fissure  of  the  spleen,  which  is  filled  by 
vessels  and  a certain  quantity  of  fat. 

ORGANIZATION  OF  THE  SPLEEN. 

It  is  of  a spongy  consistence  : it  aKvays  contains  a very 
large  proportion  of  blood,  which  seems  identified  with  its 
tissue,  and  which  is  found  not  only  in  its  vessels,  but  also 
in  the  very  numerous  cellules  and  areoloe  of  which  this 
organ  is  chiefly  formed.  It  contains  also  a number  of  soft 
grayish,  semitransparent  granulations,  disseminated  irregu- 
larly in  its  tissue.  Malphighi  considers  them  small  glands, 
but  their  nature  is  quite  unknown. 

Sometimes  two  or  more  small  bodies,  of  the  same  color 
and  structure  of  the  spleen,  are  found  in  its  vicinity,  be- 
tween the  laminae  of  the  omentum. 


OFFICE  OF  THE  SPLEEN. 

Regarding  the  office  of  the  spleen,  there  has  been  a 
number  of  speculations;  I shall  only  refer  to  some  of  the 
most  plausible,  and  those  which  meet  with  the  most  gen- 
eral support.  Dr.  Haighton  advanced  it  as  his  opinion, 
that  the  spleen  was  subservient  to  digestion,  by  occasioning 
an  increased  secretion  of  the  gastric  and  pancreatic  fluids, 
at  the  precise  time  when  they  are  most  required.  In  ex- 
plaining the  mode  in  which  this  effect  is  to  be  produced, 
he  agreed  with  Haller  in  the  opinion,  that  the  stomach, 
when  distended  with  food,  makes  sufficient  pressure  on 
the  spleen,  to  prevent  the  ordinary  supply  of  its  cells,  and 
to  direct  the  blood,  commonly  sent  to  it,  to  the  stomach 
itself,  and  to  the  pancreas. 

It  is  suggested  by  Sir  Astley  Cooper,  that  it  is  a part 


244 


ORGANS  OF  SECRETION. 


of  the  function  of  tlie  spleen  to  elaborate  venous  blood, 
and  thus  assist  the  liver  in  the  formation  of  bile. 

Sir  C.  Bell  also  regards  it  “ as  a provision  for  giving 
the  vessels  of  the  stomach  an  occasional  power  and  greater 
activity,  enabling  them  to  pour  out  a quantity  of  fluid  pro- 
portioned to  the  necessity  of  digestion.” 

My  talented  and  indefatigable  friend,  Dr.  Hodgkin,  has 
devoted  much  attention  to  this  subject,  and  from  consider- 
ing the  situation  and  structure  of  the  spleen  — the  differ- 
ent appearances  which  it  assumes,  according  to  the  cir- 
cumstances under  which  death  has  taken  place  — the 
causes  which  derange  it,  and  the  effects  which  it  produces 
on  the  system  when  deranged  — together  with  the  result  of 
experiments  made  on  inferior  animals  — he  has  been  in- 
duced to  adopt  a very  different  opinion  : he  believes,  “ that 
the  spleen  performs,  in  the  animal  system,  a similar  office 
to  that  which  tubes  and  valves  of  safety  do  in  various  chem- 
ical and  mechanical  apparatuses.”  By  this  comparison  he 
(Dr.  Hodgkin)  would  wish  it  to  be  understood  ; “ that  the 
spleen  tends  to  obviate  any  inconvenience  which  might 
arise  from  a sudden  disturbance  of  the  proportion  between 
the  capacity  of  the  vascular  system,  and  the  fluids  which 
circulate  in  it.  These  disturbances,”  he  adds,  “ must,  I 
conceive,  be  frequently  induced  by  various  causes  to 
which  the  animal  system  is  continually  exposed,  and 
which  operate  more  powerfully  than  the  elasticity  of  the 
vessels  alone  can  compensate  for,  and  more  readily  than 
absorption,  secretion,  and  excretion  can,  in  every  case, 
counteract.” 


ORGANS  OF  SECRETION. 


245 


SUPRA-RENAL  CAPSULES. 

F'g  85.  supra-renal  capsules,  Fig. 

85,  are  two  small  bodies,  situated 
above  the  kidneys  ; they  are  of  a 
light  brown  color,  and  consist  of 
a small  bag,  the  exterior  of  which 
is  granulated  and  collected  into 
lobules.  In  its  interior  we  ob- 
serve a narrow,  smooth,  triangular  cavity,  without  any 
known  orifice  : it  is  furnished  in  its  inferior  part  with  a 
prominent  ridge,  and  it  contains,  in  the  foetus,  a consider- 
able quantity  of  a reddish  viscid  albuminous  fluid.  In 
after  life  this  fluid  is  of  a deeper  color. 

The  office  of  these  capsules  has  hitherto  eluded  research  ; 
their  volume  is  much  greater  in  the  foetus  than  in  the  adult. 
On  this  account  it  is  supposed  that  they  have  some  con- 
nection with  the  exercise  of  nutrition  in  the  first  stages  of 
life,  or  that  these  organs  are  useful  in  the  foetal  state,  by 
deriving  the  blood  from  the  kidneys,  those  glands  not  then 
having  undertaken  their  proper  functions  of  secreting 
urine. 


THE  KIDNEYS. 

The  Tddneys  are  two  glandular  bodies,  situated  in  the 
lumbar  regions,  on  the  sides  of  the  vertebral  column,  op- 
posite the  two  last  do*-sal  and  the  two  first  lumbar  verte- 
brae. The  right  kidney  is  placed  at  the  under  and  back 
part  of  the  large  lobe  of  the  liver,  and  is  usually  a little 
lower  than  the  left  kidney  ; the  latter  is  placed  under  the 
back  part  of  the  spleen,  and  behind  the  left  portions  of 
the  stomach,  pancreas,  and  colon. 


246 


ORGANS  OF  SECRETION. 


The  kidney  is  four  or  five  inches  in  length,  and  in  shape, 
as  we  may  see  in  the  following  figures,  resembles  the  kid- 
ney bean  which  is  named  from  it. 

It  is  totally  imbedded  in  a very  solid  and  more  or  less 
thick  mass  of  fat.  This  adipose  tunic  is  extended  likewise 
to  the  renal  vessels,  and  is  supposed  to  defend  them  from 
the  pressure  of  the  surrounding  viscera. 

The  right  kidney  is  connected  to  the  liver,  the  left  to 
the  spleen,  and  both  to  the  muscles  on  which  they  are 
placed,  and  to  the  supra-renal  glands  and  colon  by  cellular 
tissue  : the  peritonaeum  is  reflected  from  the  liver  and  the 
spleen  to  the  kidneys. 

ORGANIZATION  OF  THE  KIDNEYS. 

The  surface  of  the  kidney  is  usually  smooth  and  uniform, 
though  sometimes  it  is  irregular,  in  consequence  of  the 
lobes  which  originally  form  it  not  being  so  completely  in- 
corporated. Each  kidney  receives  from  the  aorta  an 
artery  of  considerable  diameter,  and  returns  its  blood  by  a 
large  vein  into  the  inferior  vena  cava.  A very  distinct 
nervous  plexus  surrounds  these  vessels,  and  the  lympha- 
tics are  very  easily  to  be  traced. 

The  kidney  appears  to  be  formed  of  two  distinct  sub- 
stances ; an  external  or  cortical,  and  an  internal  tubular, 
or  medullary  substance. 

The  cortical  substance  of  the  kidneys  forms  the  external 
layer  of  these  organs,  and  internally  it  is  prolonged  into 
them  in  the  form  of  septa,  between  which  we  find  the 
conical  fasciculi  of  the  tubular  substance.  When  viewed 
with  a microscope,  the  cortical  substance  appears  composed 
of  solid  granulations  of  a very  small  size,  formed  by  the 
capillary  extremities  of  the  renal  arteries  and  veins. 

The  tubular  substance  presents  a number  of  conical  fas- 


ORGANS  OF  SECRETION. 


247 


ciculi,  surrounded  on  all  sides,  except  at  their  summits,  by 
the  cortical  substance.  The  base  of  each  cone  is  directed 
towards  the  circumference  of  the  kidney,  and  their  summits, 
on  the  contrary,  are  directed  towards  the  pelvis,  or  fissure 
of  the  kidney. 

The  color  of  this  substance  is  a pale  red  ; its  tissue  is 
dense  and  is  formed  of  a multitude  of  very  minute  conver- 
gent canals,  termed  tubuli  uriniferi,  which  derive  their  ori- 
gin from  the  cortical  substance,  and  terminating  in  larger 
ducts  at  the  summits  of  the  cones,  present  so  many  mam- 
mill®,*  at  the  points  of  which  the  urine  oozes  out.  The 
number  of  mammill®  is  twelve  or  fourteen  ; the  orifices  of 
the  canals  (called  the  ducts  of  Belini)  of  the  tubular  sub- 
stance are  less  numerous  than  the  canals  themselves,  on 
which  account  it  is  to  be  presumed  that  several  of  these 
uriniferous  tubes  unite  before  they  terminate. 


THE  CALYCES,  PELVIS,  AND  URETER. 

The  calyces,  or  infundibula,  are  membranous  tubes  which 
embrace  the  mamrnill®,  and  which  receive  the  urine  from 
them.  The  infundibula  are  commonly  the  same  in  num- 
ber as  the  mammillae  ; the  number,  however,  varies  in  dif- 
ferent subjects,  two  or  more  mammill®  sometimes  opening 
into  the  same  infundibulum. 

The  pelvis  is  a membranous  bag  formed  by  the  union  of 
the  infundibula;  it  is  contracted  at  the  inferior  part  to  be 
continued  into  the  ureter. 

The  uretej-s,  or  the  excretory  ducts  of  the  kidneys  are 
long  membranous  canals,  of  a cylindrical  form,  and  about 
the  size  of  a writing  quill ; each  extends  from  the  pelvis  of 
the  kidney,  with  which  it  is  continuous,  to  the  fundus  of 
the  bladder  into  which  it  opens. 


Frequently  termed  papillcc. 


248 


ORGANS  OF  SECRETION. 


The  uterers  descend  in  the  loins  obliquely  inwards  be- 
hind the  peritonaeum,  and  over  the  psoas  and  iliac  muscles, 
and,  passing  into  the  pelvis,  terminate  in  the  under,  outer, 
and  back  part  of  the  bladder,  by  a narrow  oblique  orifice. 

The  infundibula,  pelvis  and  ureters  appear  to  have  the 
same  organization  ; being  composed  of  two  membranes, 
namely,  an  outer,  thick,  white,  opaque  membrane,  which 
may  be  considered  as  a prolongation  of  the  fibrous  capsule 
of  the  kidney  ; and  an  inner,  mucous,  transparent  mem- 
brane, which  is  extended  from  the  infundibula  over  the 
mammillfe,  and  perhaps  even  introduced  into  the  urinife- 
rous  tubes. 

Where  the  ureters  open  into  the  bladder,  some  few  pale 
muscular  fibres  may  in  general  be  found.  These  have 
been  named  the  muscles  of  the  ureters,  by  Sir  Charles 
Bell,  who  describes  each  as  arising  from  the  vesical  ex- 
tremity of  the  ureter,  and  thence  descending  obliquely  for- 
wards and  inwards,  to  be  inserted  by  a tendon  common  to 
its  fellow  into  the  tubercle  or  uvula  of  the  urethra.  The 
use  which  he  assigns  to  them  is,  to  restrain  the  termination 
of  the  ureters,  and  preserve  the  obliquity  of  the  passage  of 
these  tubes  through  the  coats  of  the  bladder  when  it  is 
contracted  ; for  without  this  provision,  he  remarks,  the 
urine  would  be  sent  retrograde  into  the  ureters,  instead  of 
forward  into  the  urethra. 


OUGANS  OF  SECRETION. 


249 


Fig.  86. 


Fig.  86,  exhibits  a section  of  the  kidney. 
a,  the  cortical  substance. 
i,  the  tubular  substance. 

c,  the  mammillse,  around  which  are  the  infundibula. 

d,  the  pelvis. 

e,  the  ureter. 

/,  the  renal  artery. 
g,  the  renal  vein. 


VOL.  II. 


32 


260 


ORGANS  OF  SECRETION. 


THE  BLADDER. 

The  urinary  bladder  is  a musculo-membranous  reser- 
voir, whose  office  it  is  to  retain  for  some  time  the  urine 
which  is  afterwards  to  be  ejected  from  it.  The  bladder 
is  situated  in  the  pelvis  at  the  bottom  of  the  hypogastric 
region. 

The  superior  part  of  the  bladder  is  in  contact  with  the 
inferior  convolutions  of  the  small  intestine ; and  from  its 
centre  we  observe  a fibrous  cord  termed  the  urachus, 
which  ascends  between  the  linea  alba  and  the  peritonaeum 
to  the  umbilicus,  where  it  terminates  in  the  abdominal 
aponeurosis. 

The  inferior  part  or  fundus  of  the  bladder,  in  the  male, 
is  connected  by  cellular  tissue  to  the  vesiculae  seminales, 
and  the  end  of  the  vasa  deferentia.  That  portion  of  the 
bladder,  which  is  between  the  two  vesiculae,  rests  upon  the 
rectum.  In  the  female  the  bladder  is  connected  with  the 
levator  ani  and  the  vagina. 

The  anterior  part  is  situated  behind  the  pubes,  but  when 
the  organ  is  distended  by  urine,  we  find  it  in  the  hypo- 
gastric region.  Their  is  a fasciculus  of  fibrous  mem- 
brane which  attaches  the  anterior  part  of  the  bladder  to  the 
symphysis  of  the  pubes,  named  the  anterior  ligament  of  the 
bladder. 

The  posterior  part  is  entirely  covered  by  the  peritonaeum, 
and  is  contiguous,  in  the  male,  to  the  rectum,  and  in  the 
female,  to  the  uterus. 

The  internal  surface  of  the  bladder  is  formed  by  a 
mucous  membrane,  which,  in  its  empty  state,  presents 
numerous  irregular  rugae,  but  these  disappear  when  the 
bladder  is  full  ; and  we  always  find  on  the  fundus  a re- 
markable triangular  space  where  the  mucous  membrane  is 


ORGANS  OF  SECRETION. 


251 


destitute  of  rugae ; it  is  named  the  trigonal  space  of  the 
bladder. 

The  neck  of  the  bladder  has  a crescent-like  form,  the 
margin  of  which  is  very  thick,  and  it  embraces  a small 
tubercle,  designated  by  the  name  of  the  uvula  vesicce. 


THE  ORGANIZATION  OF  THE  BLADDER. 

The  pei'itonceal  membrane  is  reflected  over  part  of  the 
superior,  posterior  and  lateral  portions  of  the  bladder,  and 
it  is  united  to  the  muscular  membrane  by  loose  cellular 
tissue. 

The  muscular  membrane  consists  of  muscular  fibres, 
spread  out  in  various  directions  over  the  bladder ; the 
greater  number,  however,  are  longitudinal,  a few  only 
being  transverse.  These  fibres  are  stronger  on  the  an- 
terior and  posterior  surfaces  than  on  the  sides.  On  the 
latter  region  they  run  obliquely.  The  anterior  fibres, 
from  having  a fixed  attachment,  are  called  by  some  anato- 
mists the  detrusor  urinre  muscle. 

The  neck  of  the  bladder  is  formed  of  a firm,  white, 
extensile,  fibrous  membrane,  with  muscular  fibres,  having 
the  same  arrangement  as  on  the  bladder  itself ; this  is  gen- 
erally designated  by  anatomists  as  the  sphincter  vesicae.  J. 
Cloruet  altogether  denies  that  it  is  a sphincter  muscle, 
and  states  it  to  be  merely  the  fleshy  fibres  brought  closer 
together  than  elsewhere. 

The  cellular  membrane  is  that  which  connects  together 
the  mucous  and  muscular  structure  of  the  bladder,  and 
in  which  we  observe  the  most  numerous  vessels  and 
nerves. 

The  mucous  membrane  is  continuous  with  the  inner 
surface  of  the  ureters  and  the  urethra.  Its  villosities  are 


252 


ORGANS  OF  SECRETION. 


very  delicate  and  not  easily  detected  : in  its  natural  state 
no  mucous  follicles  are  to  be  observed,  but  in  certain  mor- 
bid conditions  their  presence  is  very  apparent. 

THE  OFFICE  OF  THE  KIDNEYS  AND  THE  BLADDER. 

The  kidneys  separate  the  urine  from  the  blood,  and 
convey  it  by  means  of  the  ureters  to  the  bladder.  There 
is  every  reason  to  suppose  that  substances  hurtful  to 
the  animal  economy  are  discharged  in  this  fluid ; for 
when  there  is  a total  suppression  of  this  secretion,  or 
when  the  renal  arteries  are  tied,  death  occurs  in  a short 
space  of  time. 

When  the  pelvis  of  a kidney  is  cut  open,  in  the  liv- 
ing animal,  the  urine  may  be  seen  to  pass  out  slowly 
at  the  points  of  the  excretory  cones.  Or  if  we  remove 
the  kidney  from  the  body,  and  compress  the  urinife- 
rous  cones,  we  observe  a considerable  quantity  of  this 
fluid  issuing  from  them.  The  urine  then  enters  the  pelvis 
of  the  kidney,  and  by  small  quantities  proceeds  through 
the  ureter  by  a constant  exudation,  and  slowly  distends 
the  bladder.  The  urine  is  prevented  from  flowing  back 
into  the  ureters,  by  these  conduits  passing  a consider- 
able distance  into  the  sides  of  the  bladder,  so  that,  in 
proportion  as  the  urine  distends  this  organ,  it  compresses 
the  ureters,  and  closes  them  more  firmly  as  it  is  more 
abundant.  This  mechanism  may  be  observed  in  the 
dead  body,  for  if  we  inject  the  bladder  with  water  or 
even  air,  by  the  urethra,  we  find  that  it  never  enters  the 
ureters. 


ORGANS  OF  SECRETION. 


253 


THE  URINE. 

There  is  no  fluid  of  the  human  body  so  variable  with 
respect  to  quantity  and  quality ; for  it  varies  according 
to  age,  to  the  quantity  of  fluids  drank,  the  nature  of 
the  aliments  or  medicines  taken,  or  according  to  the  sea- 
son of  the  year  : in  the  winter  it  is  more  copious,  and  in 
the  summer,  from  the  increased  transpiration,  it  is  more 
sparing  and  high  colored.  Affections  of  the  mind  also 
influence  the  secretion ; thus  fright  makes  the  urine  pale 
and  copious. 

The  numerous  researches  made  concerning  urine  have 
given  the  following  as  its  component  parts : 1 water ; 2 
urea ; 3 phosphoric  acid ; 4,  5,  6,  7,  phosphates  of  lime, 
magnesia,  soda,  and  ammonia;  8,  9, 10,  11,  lithic,  rosacic, 
benzoic,  and  carbonic  acid  ; 12  carbonate  of  lime  ; 13,  14, 
muriates  of  soda  and  ammonia  ; 15  gelatin  ; 16  albumen  ; 
17  resin  ; 18  sulphur.* 

* Dr.  Ure. 


254 


ORGANS  OF  SECRETION, 


According  to  Berzelius  the  following  are  the  ingredi- 
ents of  1000  parts  of  healthy  urine. 


Water, 933*00 

Urea, 30*10 

Sulphate  of  potass, 3*71 

Sulphate  of  soda, 3*16 

Phosphate  of  soda, 2*94 

Muriate  of  soda, 4*45 

Phosphate  of  ammonia,  ....  1*65 

Muriate  of  ammonia, 1*50 

Free  lactic  acid — ^ lactate  of  ammonia 
— animal  matter  soluble  in  alco- 
hol — urea  not  separable  from  the 

preceding, 17*14 

Earthy  phosphate,  with  a trace  of 

fluate  of  lime,  1*00 

Uric  acid, 1*00 

Mucus  of  the  bladder, 0*32 

Silex, 0*03 


1000*00 


ART.  XIII. 


ORGANS  OF  GENERATION  IN  THE  MALE. 

These  consist  of  the  testicles  and  their  appendages,  the 
vesiculas  seminales,  the  prostate,  the  ductus  ejaculatorii, 
and  the  penis. 

THE  TESTICLES  AND  THEIR  APPENDAGES. 

1.  THE  ENVELOPES  OF  THE  TESTICLES. 

1st.  The  scrotum,  or  the  cutaneous  envelope  of  the  tes- 
ticles, is  a continuation  of  the  skin  of  the  adjacent  parts. 
It  is  remarkable  for  having  a deeper  color  than  other  parts 
of  the  skin,  for  the  great  number  of  mucous  follicles  which 
it  contains  in  its  substance,  and  for  its  long  and  scattered 
hairs  which  are  inserted  obliquely,  and  so  superficially  that 
their  bulbs  produce  distinct  elevations  of  the  skin.  Upon 
the  surface  of  the  scrotum  there  is  a superficial,  longitudi- 
nal, elevated  line,  called  the  raphe,  which  divides  it  into 
two  equal  parts,  and  extends  as  far  as  the  anterior  part  of 
the  anus. 


256  ORGANS  OF  GENERATION  IN  THE  MALE. 

2d.  The  dartos  is  a filamentous  cellular  membrane  of  a 
rose  color,  entirely  destitute  of  adipose  substance,  in 
which  an  infinite  number  of  vessels  are  distributed ; and 
although  some  authors  have  described  it  as  a muscle,  it 
certainly  does  not  exhibit  the  smallest  appearance  of  mus- 
cular fibres.  It  is  attached  to  the  ischium  and  pubes ; 
meeting  in  the  middle  that  of  the  opposite  side,  thus  form- 
ing a septum  which  separates  the  testicles.  The  inner  sur- 
face is  applied  to  the  fibrous  tunic  of  these  organs,  and  on 
the  extremity  of  the  cremaster  muscle ; the  outer  surface 
adheres  to  the  scrotum. 

3d.  The  cremaster  muscle.  This  has  been  already  de- 
scribed. See  Vol.  I.  page  213,  Fig.  131. 

4th.  The  fibrous  tunic  is  thin,  transparent  and  very 
little  resistant;  it  forms  an  elongated  sac,  placed  within 
each  dartos.  Superiorly,  it  forms  a sheath  for  the  sper- 
matic cord,  and,  inferiorly,  it  contains  the  testicle  and  epi- 
didymis. 

5th.  The  tunica  vaginalis,  a serous  membrane  which 
constitutes,  like  all  other  serous  membranes,  a sac  without 
an  opening ; it  covers  the  whole  internal  surface  of  the 
fibrous  tunic,  and  is  extended  to  the  epididymis  and  tes- 
ticle ; entirely  covering  the  latter  excepting  at  its  upper 
edge.  In  infancy  it  is  manifestly  continuous  with  the  peri- 
tonaeum, having  descended  with  it  into  the  scrotum.  This 
circumstance  explains  the  formation  of  that  species  of 
hernia  in  which  the  intestine  is  in  immediate  contact  with 
the  testicle. 

9.  THE  TESTICLES. 

The  testicles  are  two  ovoid  glandular  organs,  lodged  in 
the  scrotum.  The  right  testicle  is  generally  a little  higher 
than  the  left. 


ORGANS  OF  GENERATION  IN  THE  MALE.  257 


ORGANIZATION  OF  THE  TESTICI.E. 

The  tunica  albuginea  is  a fibrous  membrane,  white  and 
opaque,  not  unlike  the  sclerotica ; it  serves  as  a direct  en- 
velope to  the  testicle.  Its  outer  surface  is  covered  by  the 
serous  membrane  ; its  inner  is  applied  upon  the  proper 
substance  of  the  testicle,  and  sends  into  the  interior  of  it 
a number  of  delicate  prolongations,  directed  towards  its 
posterior  part.  These  septa  divide  the  testicle  into  several 
cells  which  contain  the  seminal  vessels. 

On  the  inner  side  of  this  membrane  we  observe  the 
corpus  Highmorianum,  an  elongated  prominence  at  the 
superior  part  of  the  testicle,  across  which  the  principal 
trunks  of  the  seminal  vessels  pass  obliquely  towards  the 
epididymis. 

The  parenchyma  of  the  testicle  is  soft,  of  a gray  color 
marbled  with  red,  and  is  formed  of  an  immense  number 
of  very  minute  tortuous  tubes,  slightly  connected  to  each 
other.  According  to  the  observations  of  Monro,  they  do 
not  exceed  the  two  hundredth  part  of  an  inch  in  diame- 
ter ; these  tubes,  termed  vasa  seminalia,  or  tubuli  semini- 
feri,  do  not  ramify,  but  their  length  is  very  great ; the 
same  author  estimates  their  number  at  about  sixtytwo 
thousand  five  hundred,  and  he  considers  their  total 
length  to  be  five  thousand  two  hundred  feet : capillary 
arteries  and  veins  of  still  greater  minuteness  are  observed 
among  them. 

The  seminal  ducts  just  described  are  all  directed  towards 
the  superior  part  of  the  testicle,  where  they  form  from 
twenty  to  thirty  considerable  trunks,  which  traverse  the 
corpus  Highmorianum,  opposite  and  a little  below  the  epi- 
didymis, where  they  dilate  and  give  origin  to  the  duc.t 
which  forms  the  epididymis. 

VOL.  II.  33 


25S  ORGANS  OF  GENERATION  IN  THE  MALE. 


3.  EPIDIDYMIS. 

This  name  Is  given  to  the  canal  formed  by  the  union  of 
all  those  smaller  tubes,  which  compose  the  body  of  the 
testes  and  the  corpus  Highmorianum.  The  epididymis  is 
situated  upon  the  upper  part  of  the  testicle,  is  inclosed  in 
the  same  covering  with  it,  and  is  exceedingly  convoluted 
until  it  passes  into  the  spiermatic  cord.  Its  superior 
part  arises  from  the  corresponding  part  of  the  testicle, 
where  it  receives  the  vasa  efferentia ; its  inferior  part  is 
adherent  to  the  testicle,  and  is  continuous  with  the  vas 
deferens;  its  middle  portion  is  adherent  to  the  testicle. 

4.  VAS  DEFERENS. 

The  vas  deferens  is  the  large  excretory  duct  of  the  testi- 
cle. It  commences  at  the  lower  part  of  the  epididymis, 
ascends,  describing  many  flexuosities,  behind  the  testicle, 
and  immediately  enters  the  spermatic  cord,  where  it  is  pla- 
ced behind,  and  internally  to  the  artery  and  nerves  which 
accompany  it.  After  passing  the  ring  it  leaves  the  other 
vessels  of  the  cord,  and  descends  backwards  and  inwards 
upon  the  side  of  the  bladder.  Then,  arriving  under  the 
inferior  and  posterior  region  of  the  bladder,  it  approaches 
its  fellow,  and  proceeds  along  the  inner  edge  of  the  vesi- 
cul®  seminales.  At  the  base  of  the  prostate  gland,  it  re- 
ceives a canal  from  the  vesiculae  seminales,  and  is  continued 
into  the  ejaculatory  duct. 

The  vas  deferens  is  slender  near  its  origin,  but  on  pass- 
ing through  the  abdominal  ring  it  increases  in  size,  and 
becomes  twice  as  large  along  the  vesiculae  seminales  : at 
its  termination,  however,  it  resumes  its  original  size.  The 
parietes  of  this  duct  are  very  thick,  and  have  almost  a 


ORGANS  OF  GENERATION  IN  THE  MALE.  259 


cartilaginous  consistence  ; its  cavity  is  so  small  as  scarcely 
to  admit  a hair,  except  near  the  vesiculas,  where  it  is  much 
larger. 


5.  SPERMATIC  CORD. 

The  spermatic  cord  is  composed  of  the  last  mentioned 
duct,  namely,  the  vas  deferens,  the  spermatic  artery  and 
vein,  of  some  other  inconsiderable  and  irregular  blood 
vessels,  lymphatics,  and  nerves.  It  is  enveloped  by 
several  membranous  layers,  and  contains  a large  quan- 
tity of  cellular  tissue  in  the  intervals  of  its  component 
parts.  It  ascends  from  the  upper  part  of  the  testicle, 
and  enters  into  the  abdomen  by  the  inguinal  ring.  The 
organs  of  which  it  is  composed  then  separate  from  each 
other,  and  follow  a course  with  which  we  are  already  ac- 
quainted. 


260 


ORGANS  OF  GENERATION  IN  THE  MALE. 


Fig.  87.  Posterior  view  of 
tlie  testis  and  tunica  vagina- 
lis. 

a,  the  spermatic  cord. 

b,  the  vas  deferens. 

c,  the  commencement  of  the 
epididymis. 

J,  the  testis  devoid  of  the 
tunica  vaginalis. 

c,  the  tunica  vaginalis. 


Fig.  87. 
a h 


THE  VESICUL^  SEMINALES,  PROSTATE,  COWPER’S  GLANDS, 
AND  DUCTUS  EJACULATORH. 


1.  VESICUL7E  SEMINALES. 

The  vesiculee  seminales  are  situated  beneath  the  blad- 
der, in  front  of  the  insertion  of  the  ureters,  and  on  the 
outer  side  of  the  vas  deferens.  They  are  two  membra- 
nous reservoirs  about  two  inches  and  a half  in  length,  and 
six  or  seven  lines  in  breadth.  In  dried  preparations  the 
vesicula3  appear  as  a cavity  composed  of  numerous  cells  ; 
but  if  they  are  carefully  dissected  they  present  a fiexuous 
canal. 


ORGANS  OF  GENERATION  IN  THE  MALE.  261 


These  vesiculse  are  filled  with  a thick  yellowish  fluid, 
which  has  been  supposed  to  have  retrograded  from  the  vasa 
deferential  but  as,  in  some  animals,  the  vesiculae  seminales 
have  no  connection  with  the  excretory  ducts  of  the  testes, 
we  may  reasonably  infer  that  they  are  not  mere  receptacles 
of  the  secretion  of  the  testicles.  The  vesiculae  are  organs 
of  secretion,  producing  a peculiar  fluid  which  is  ejected  at 
the  same  moment  as  the  secretion  just  mentioned. 

2.  PROSTATE  GLAND. 

The  prostate  gland  is  a body  of  the  size  and  figure  of  a 
chesnut,  formed  of  an  assemblage  of  mucous  follicles  sur- 
rounding the  neck  of  the  bladder  and  the  commencement 
of  the  male  urethra. 

This  gland  has  a division  forming  it  into  two  lateral  lobes, 
and  there  is  sometimes  an  inferior  lobe  at  the  base  of  the 
prostate,  first  noticed  by  Morgagni,  and  subsequently  very 
particularly  described  by  Sir  Everard  Home.  It  is  called 
lohus  Morgagni. 

The  upper  surface  is  covered  by  the  inferior  ligament  of 
the  bladder;  the  lower  surface  rests  upon  the  rectum.  Its 
base  forms  a very  remarkable  prominence  round  the  neck 
of  the  bladder  ; its  summit  terminates  upon  the  membra- 
nous portion  of  the  urethra. 

The  prostate  gland  is  of  a light  gray  color,  and  its  struc- 
ture is  very  dense  and  firm  ; it  is  filled  with  a great  number 
of  small  follicles  containing  a viscid  fluid.  From  these 
follicles  ten  or  fifteen  excretory  ducts  arise  and  open  into 
the  urethra,  on  the  sides  and  at  the  surface  of  the  Veru- 
montanum.  When  we  remove  this  gland  from  the  dead 
body  and  compress  it,  the  fluid  it  contains  is  made  to  issue 
from  the  orifices  of  these  ducts. 


262  ORGANS  OF  GENERATION  IN  THE  3IALE. 


3.  COWRER’S  GLANDS. 

These  are  two  small  granulated  glandular  bodies,  placed 
parallel  to  each  other  before  the  prostate.  They  are  of  a 
red  color,  about  the  size  of  a pea,  and  of  a structure 
resembling  the  salivary  glands.  Each  of  these  glands  has 
an  e.xcretory  duct,  which  proceeds  obliquely  inwards  and 
forwards  in  the  spongy  tissue  of  the  urethra,  and  opens 
before  the  Verumontanum.  These  glands  are  for  the  pur- 
pose of  secreting  a mucus,  to  be  discharged  into  the  urin- 
ary passage. 

4.  EJACUL.VTORY  DUCTS. 

These  ducts  commence  at  an  acute  angle,  formed  by  the 
junction  of  the  vasa  deferentia  with  those  which  terminate 
the  vesiculae  seminales  ; they  are  about  an  inch  in  length, 
and  proceed  parallel  to  each  other,  in  the  substance  of  the 
prostate  gland,  opening  into  the  urethra  by  two  small  ob- 
long orifices,  situated  upon  the  lateral  and  anterior  part  of 
the  Verumontanum. 


ORGANS  OF  GENERATION  IN  THE  MALE,  263 


Fig. 


Fig.  88j  exhibits  the  urinary  bladder  inflated,  and  the 
principal  parts  of  the  organs  of  generation  of  the  male. 

a,  the  peritonaeum  covering  the  bladder. 

b,  the  muscular  membrane  of  the  bladder. 

c,  the  corpus  cavernosum  penis. 

d,  the  corpus  spongiosum  urethrae. 

e,  the  bulb  of  the  urethra. 

f,  one  of  Covvper’s  glands. 

g,  the  prostate  gland  surrounding  the  neck  of  the 
bladder. 

Zr,  the  inferior  lobe  of  the  prostate  gland. 
i,  i,  the  vesiculae  semina'les. 

/,  I,  the  testes. 


264  ORGANS  OF  GENERATION  IN  THE  MALE. 


m,  m,  vas  deferens. 

ti,  the  membranous  portion  of  the  urethra. 

0,  the  right  crus  of  the  penis. 

p,  the  ureter  terminating  in  the  bladder. 

PENIS. 

The  penis  is  formed  by  the  corpus  cavernosum,  the 
urethra,  the  corpus  spongiosum  urethra,  terminated  by  the 
glans ; the  vessels,  nerves,  and  a cutaneous  investment,  which, 
by  its  prolongation,  forms  the  prepuce. 


1.  INTEGUMENTS  OF  THE  PENIS  AND  PREPUCE. 

These  parts  are  merely  a continuation  of  the  common 
integuments,  which  are  here  more  delicately  thin,  and  in- 
stead of  fat,  there  is,  as  in  the  scrotum,  only  a cellular 
tissue. 

At  the  anterior  extremity  of  the  penis  the  integuments 
form  a greater  or  less  prolongation,  which  is  termed  the 
prepuce,  which  covers  the  glans  when  the  penis  is  in  a 
state  of  relaxation.  The  prepuce  is  connected  to  the  un- 
der part  of  the  glans  by  a triangular  fold,  termed  the  frce- 
num  preputii. 

The  prepuce  is  composed  of  two  membranous  layers, 
between  which  is  a plane  cellular  tissue  ; the  outer  layer  is 
formed  by  the  skin  ; the  inner  is  of  the  nature  of  a mucous 
membrane,  and  is  furnished  with  sebaceous  follicles,  term- 
ed the  glandula  odorijirce. 


2.  CORPUS  CAVERNOSU-M. 

Most  writers  on  anatomy  describe  two  corpora  caver- 
nosa penis,  but  there  exists  only  one ; there  are  certainly  two 


ORGANS  OF  GENERATION  IN  THE  MALE.  265 


roots,  and  a septum  in  part  of  its  extent,  but  it  is  so  in- 
complete a partition,  that,  with  Cloq,uet,  Cuaussier  and 
others,  we  must  consider  it  as  a single  body. 

The  corpus  cavernosum  forms  about  two-thirds  of  the 
volume  of  the  penis  : it  is  placed  over  the  urethra,  and  ex- 
tends from  the  anterior  and  inner  part  of  the  sciatic  tuber- 
osity, as  far  as  the  substance  of  the  glans. 

The  roots  of  the  corpus  cavernosum  are  attached  to  the 
inner  border  of  the  ramus  of  the  ischium  and  pubes  ; they 
are  about  two  inches  in  length,  commencing  in  front  of 
the  sciatic  tuberosity,  and  uniting  at  the  inferior  part  of 
the  symphysis  pubis.  The  triangular  space  which  sepa- 
rates them  from  each  other,  is  occupied  by  fat  and  by  the 
urethra. 

The  anterior  extremity  of  the  corpus  cavernosum  is 
united  to  the  base  of  the  glans,  and  perforated  by  several 
apertures  for  the  passage  of  vessels.  Its  upper  surface  is 
marked  with  a longitudinal  groove,  in  which  we  observe 
the  dorsal  artery  and  veins  of  the  penis.  Posteriorly  it 
gives  attachment  to  the  suspensory  ligament  of  this  organ, 
being  a fibrous  fasciculus  attached  to  the  inferior  part  of 
the  symphysis  pubis.  The  inferior  surface  is  marked  by  a 
broad,  deep  groove,  which  receives  the  superior  side  of  the 
canal  of  the  urethra,  to  which  it  adheres  by  a filamentous 
cellular  tissue. 


ORGANIZATION  OF  THE  CORPUS  CAVERNOSUM. 

The  corpus  cavernosurn  is  composed  of  a very  strong 
fibrous  tunic,  of  an  opaque  white  appearance,  excepting  at 
its  roots  and  at  the  anterior  extremity,  where  its  color  is 
more  or  less  livid.  Its  fibres  are  for  the  most  part  longi- 
tudinal, and  are  interwoven  posteriorly  with  the  periosteum 
von.  II.  34 


266  ORGANS  OF  GENERATION  IN  THE  MALE. 

of  the  bones  of  the  ilium,  and  the  aponeurosis  of  the  mus- 
cles, which  are  attached  to  their  lower  edge. 

The  cavity  of  this  fibrous  membrane  is  partially  divided 
into  two  lateral  portions,  but  the  partition  does  not  extend 
beyond  two  thirds  of  its  length  ; it  is  then  continued  merely 
as  a few  fibrous  fasciculi  to  the  glans. 

The  spongy  tissue,  enveloped  by  the  preceding  mem- 
brane, appears  to  consist  of  a complicated  net-work  of  arte- 
rial and  venous  vessels,  probably  of  nerves  also,  and  of 
small  fibrous  lamina3,  which  latter  form  numerous  cellules 
communicating  with  each  other,  and  with  the  blood  vessels, 
and  always  containing  a greater  or  less  quantity  of  blood. 
An  injection  made  by  the  cavernous  artery  passes  into 
these  cellules,  and  if,  on  the  contrary,  we  inflate  these 
cellules  with  air,  it  passes  into  the  cavernous  vein,  so  that 
we  may  conclude  that  they  are  intermediate  with  the  arte- 
ries and  veins. 

3.  I tret  UK  A. 

The  urethra  extends  from  the  neck  of  the  bladder  to 
the  extremity  of  the  glans  penis  ; its  capacity  very  much 
exceeds  that  of  any  other  excretory  duct.  Its  parietes 
are  partly  spongy  and  partly  membranous.  At  first  its 
course  is  directed  a little  forwards  and  downwards  ; next 
traversing  the  prostate  gland,  it  passes  through  a circular 
aperture  of  the  triangular  ligament  of  the  bladder,  and 
under  the  symphysis  pubis  mounts  in  front  of  it  between 
the  two  roots  of  the  corpus  cavernosum,  and  then  descends 
in  the  groove,  in  the  superior  surface  of  the  latter  as  far  as 
the  summit  of  the  glans  penis,  where  it  opens  by  a vertically 
elongated  orifice.  It  is  distinguished  into  three  portions  : 

1st.  The  prostatic  portion,  which  is  from  fifteen  to 
eighteen  lines  in  length,  and  passes  obliquely  through  the 
prostate  gland. 


ORGANS  OF  GENERATION  IN  THE  MALE.  267 


2d.  The  membranous  portion  is  thin  and  contracted ; it 
is  from  eight  to  ten  lines  in  length,  and  united  to  the  rec- 
tum inferiorly  and  posteriorly,  and  anteriorly  approaching 
the  inferior  part  of  the  symphysis  pubes. 

3d.  The  spongy  portion  commences  posteriorly  by  the 
bulb  of  the  urethra,  which  is  situated  beneath  the  angle  of 
union  of  the  roots  of  the  corpus  cavernosum.  Anteriorly 
it  expands  to  form  the  glans  penis. 

The  cavity  of  the  urethra  has  not  the  same  dimensions 
through  its  whole  extent ; it  is  rather  broad  at  its  origin  ; 
it  contracts  and  again  dilates  in  the  centre  of  the  prostate 
gland.  The  membranous  portion  is  much  narrower  than 
any  other  part  of  the  canal,  and  in  its  spongy  portion  its 
breadth  is  very  nearly  equal  except  towards  its  extremity, 
where  there  is  a remarkable  dilation,  termed  the  fossa  na- 
vicularis. 

The  interior  of  the  urethra,  through  the  whole  length 
of  the  canal,  presents  two  white  lines,  the  one  superior,  the 
other  inferior ; the  latter  line  terminates  posteriorly  in  a 
prominence,  about  an  inch  long,  named  the  verumontanum, 
or  the  caput  gallinaginis,  continuous  posteriorly  with  a 
small  fold  of  the  mucous  membrane : the  orifices  of  the 
ejaculatory  ducts  open  at  its  sides  ; those  of  the  prostate  on 
its  surface,  and  those  of  Cowper’s  glands  in  front  of  it. 

ORGANIZATION  OF  THE  URETHRA. 

The  mucous  lining  of  the  urethra  is  continuous  at  the 
one  extremity  with  that  which  covers  the  glans,  and  at 
the  other,  with  the  mucous  membrane  of  the  bladder.  Its 
color  is  a bright  red  near  its  orifice,  but  it  becomes  pale 
and  white  through  the  remainder  of  its  extent.  A great 
number  of  small  foramina  are  observed  opening  on  its  sur- 
face, named  sinuses  of  Morgagni  ; and  by  a folding  of  the 


268  ORGANS  OF  GENERATION  IN  THE  MALE. 


membrane  they  form  so  many  lacunae,  commencing  at  the 
bulb  and  becoming  more  numerous  towards  the  fossa  navi- 
cularis. 

The  s]}07ig^  tissue  surrounds  the  three  anterior  fourths 
of  the  length  of  the  urethra  ; it  is  somewhat  thick  at  the 
bulb,  then  becomes  contracted  into  a cylindrical  tube  as  far 
as  the  glans  penis  ; this  spongy  tissue  being  expanded  so 
as  to  form  this  part. 

The  membranous  portion  of  the  urethra  is  braced  to  the 
arch  of  the  pubes  by  muscular  fibres,  discovered  by  Mr 
Wilson,  and  named  by  him  the  compressor  uretlirce  : when 
this  muscle  acts  it  compresses  the  urethra  so  as  to  close  it 
as  completely  as  a sphincter,  while,  from  its  attachments, 
it  draws  the  urethra  towards  the  pubes. 

GLANS  PENIS. 

The  glans  is  covered  by  a very  delicate  epidermis  ; and 
is  circumscribed  by  a prominent  ridge,  called  the  corona 
glandis.  Its  internal  tissue  has  the  same  characteristics  as 
the  corpus  cavernosum,  only  appearing  more  dense. 

Fig.  89,  exhibits  a section 
of  the  penis. 

a,  a,  the  corpus  caverno- 
sum penis. 

b,  the  corpus  spongiosum 
u re  three. 

c,  the  urethra. 


Fig,  89. 


ART.  XIV. 


ORGANS  OF  GENERATION,  AND  FOR  THE  NUTRITION  OF 
THE  CHILD,  IN  THE  FEMALE. 

The  genital  organs  of  the  female  consist  of  the  vulva, 
the  vagina,  and  the  uterus,  and  its  appendages. 

The  vulva,  or  pudendum,  is  the  name  given  to  the  ex- 
ternal parts  of  generation  in  the  female,  under  which  are 
comprehended  — 

1st.  lahia  pudendi,  iwo  membranous  folds,  formed 
by  a prolongation  of  the  skin,  beneath  which  there  are  a 
considerable  number  of  sebaceous  follicles.  The  integu- 
ment on  the  fore  part  of  the  symphysis  pubis  is  slightly 
elevated  by  a quantity  of  cellular  and  adipose  substance 
deposited  beneath  it,  and  is  covered  with  hair.  This  part, 
from  its  surmounting  the  labia,  has  been  called  Mans  Ven- 
eris. The  inner  surface  of  the  labia  is  a red  mucous 
membrane,  continuous  with  the  other  parts  of  the  vulva. 
The  intervening  substance,  that  is,  between  the  skin  and 
the  mucous  membrane,  consists  of  adipose  tissue  and  some 
fibres  of  the  constrictor  vaginae  muscle.  The  labia  unite 
both  beneath  the  nions,  and  before  the  perinaeum,  the 
points  of  union  being  called  commissures.  The  inferior 
one  has  also  received  the  name  of  fourchctte,  and  the  in- 


270 


OR(JAi\’ti  Ol’  GENERATION,  &c. 


lerval  between  tliis  and  the  entrance  of  the  vagina  has 
been  called  fossa  navicularis. 

2d.  The  clitoris,  a small  elongated  tubercle,  placed  at 
the  middle  and  superior  part  of  the  vulva;  it  is  supposed 
to  bear  some  analogy  to  the  penis  of  the  male,  in  having  a 
sort  of  glans  surrounded  by  a fold  of  the  mucous  mem- 
brane similar  to  the  prepuce.  It  has  also  a corpus  caver- 
nosum,  of  a spongy  texture,  adherent  by  two  roots  to  the 
rami  of  the  ischia ; it  receives  a great  quantity  of  nerves. 

3d.  The  svjmpha  are  two  membranous  crescent-like  folds, 
extending  from  the  prepuce  of  the  clitoris  to  the  middle  of 
the  orifice  of  the  vagina  ; each  of  the  nymphse  is  formed  of 
two  laminre  of  the  mucous  membrane  of  the  vulva ; they 
contain  also  in  their  substance  a small  quantity  of  spongy 
erectile  tissue. 

4th.  The  urethra  is  only  an  inch  in  length  ; it  is  wide 
at  its  commencement,  and  descends  obliquely  forwards, 
terminating  at  the  superior  part  of  the  entrance  of  the 
vagina,  by  an  orifice  called  the  meatus  urinarius  : in  its 
course  it  describes  a slight  curve,  the  concavity  of  which 
is  turned  upwards.  It  is  lined  by  a vascular  mucous  mem- 
brane, and  contains  a great  number  of  mucous  lacunae. 

5th.  The  orifice  of  the  vagina  commences  beneath  the 
meatus  urinarius ; it  is  occupied  by  the  hymen,  or  by  the 
caruncuhe  myrtiformes. 

The  hymen  is  considered  as  one  of  the  surest  signs  of 
virginity  ; it  consists  of  a more  or  less  distinct  fold  of  the 
mucous  membrane  of  the  vulva ; at  the  entrance  of  the 
vagina;  its  form  is  semilunar,  consequently  not  completely 
closing  the  opening. 

The  caruncuhe  myrtiformes  are  small  red  tubercles,  exist- 
ing only  after  the  rupture  of  the  hymen  ; they  are  in  fact 
the  remains  of  the  lacerated  hymen. 

The  vagina  is  situated  in  the  pelvis,  between  the  bladder 
and  the  rectum,  and  extends  from  the  vulva  to  the  neck  of 


IN  THE  FEMALE. 


271 


the  uterus.  It  is  from  six  to  eight  inches  long,  somewhat 
curved,  its  concavity  being  next  to  the  bladder,  therefore 
shorter  before  than  behind,  and  somewhat  more  contracted 
at  its  extremes  than  in  the  middle  part : its  position  is 
nearly  vertical,  or  rather  directed  a little  downwards  and 
forwards. 

The  outer  surface  is  invested  superiorly,  to  a small  extent, 
by  the  peritonreum ; inferiorly  it  is  contiguous  with  and 
between  the  bladder  and  rectum,  being  connected  with 
these  parts  by  a dense  cellular  tissue.  On  the  sides  it  cor- 
responds above  to  the  broad  ligaments  of  the  uterus,  and 
below  to  a mass  of  cellular  tissue  which  separates  it  from 
the  levatores  ani  muscles. 

The  internal  surface  is  covered  by  the  mucous  mem- 
brane, and  presents  numerous  transverse  wrinkles  termed 
rugcB,  which  are  less  distinct  on  the  sides,  and  are  most 
prominent  inferiorly  ; near  the  uterus  the  rugae  follow  every 
variety  of  direction.  There  are  also  two  longitudinal  ridges 
formed  by  the  mucous  membrane,  and  intersecting  the  for- 
mer at  right  angles. 

ORGANIZATION  OF  THE  VAGINA. 

The  mucous  membrane  is  continuous  with  that  of  the 
vulva  and  the  uterus.  Between  the  rugae  it  is  perforated 
by  a multitude  of  orifices  of  mucous  follicles. 

The  erectile  spongy  tissue  forms  around  the  inferior  part 
of  the  vagina,  a layer  about  an  inch  broad,  and  two  or 
three  lines  thick : it  is  described  by  De  Graaf  under  the 
name  of  retiformis,  and  by  later  anatomists  under  that  of 
the  corpus  cavernosum  vagince.  Superiorly  it  becomes  very 
thin,  but  it  may  be  traced  as  far  as  the  uterus,  and  seems 
to  be  continuous  with  the  proper  tissue  of  that  organ. 


OKttANS  OF  GENERATION,  &c 


THE  UTERUS  AND  ITS  APPENDAGES. 

The  nterus,  or  ivomb,  is  situated  in  the  middle  of  the 
pelvis,  between  the  bladder  and  rectum,  above  the  vagina, 
with  which  it  is  intimately  connected,  and  beneath  the  in- 
ferior convolutions  of  the  small  intestine.  Its  figure  is 
annexed.  It  is  flattened  from  before  backwards  and  is 
nearly  an  inch  in  thickness.  Superiorly  it  is  about  two 
inches  broad,  but  it  is  contracted  inferiorly  towards  the 
vagina,  and  terminates  by  a narrow  portion  called  the  necZr, 
to  distinguish  it  from  the  other  part  of  the  organ,  which  is 
called  its  bodi/.  The  fundus  is  the  broad  part  which  pro- 
jects above  the  attachments  of  the  Fallopian  tubes,  sur- 
mounting the  body.  It  presents  a convex  border,  and  is 
covered  by  peritonteum  in  its  entire  extent. 

The  body  of  the  uterus  is  about  two  inches  in  length  ; 
its  surfaces  are  convex,  and  invested  with  the  peritonaeum  ; 
its  anterior  part  is  in  contact  with  the  bladder,  its  posterior 
with  the  rectum.  The  cervix,  or  neck  of  the  uterxis,  is 
about  fourteen  lines  in  length,  its  transverse  diameter  from 
eight  to  ten.  Its  upper  part  is  embraced  by  the  vagina ; 
the  orifice  of  the  uterus,  called  the  os  tinea,  projects  into 
the  superior  part  of  that  canal. 

The  cavity  of  the  uterus  is  small  in  proportion  to  the 
volume  of  the  organ.  It  is  triangular  and  compressed  ; its 
edges  are  curved,  and  its  upper  angles  present  the  extremi- 
ties of  the  minute  openings  of  the  Fallopian  tubes.  Each 
of  its  surfaces  are  traversed  by  a longitudinal  slightly  ele- 
vated line.  The  cavity  of  the  cervix  is  nearly  cylindrical, 
and  somewhat  dilated  before  it  terminates  in  the  vagina. 
It  presents  a continuation  of  the  vertical  lines  I have  just 
mentioned,  and  some  faint  rugse  taking  a transverse  direc- 
tion. 


IN  THE  FEMALE. 


273 


Fig.  90. 


I 


Fig.  90,  exhibits  a section  of  the  unimpregnated  uterus, 
in  which  we  observe  the  relative  size  of  its  cavity  and  the 
thickness  of  its  parietes. 
a,  fundus  uteri. 
h,  os  tincse. 

c,  c,  a section  of  the  uterine  extremities  of  the  Fallopian 
tubes. 


ORGANIZATION  OF  THE  UTERUS. 

The  serous  membrane  is  a covering  formed  by  the  peri- 
tonseum,  which  adheres  firmly  to  its  upper  edge,  but  upon 
the  two  surfaces  it  is  separated  from  the  proper  tissue  of 
this  organ  by  a quantity  of  cellular  tissue  and  blood  ves- 
sels. In  uniting  with  the  lateral  borders,  it  forms  two 
angles,  at  the  middle  part  of  which  the  Fallopian  tubes 
terminate,  above  the  insertion  of  the  ligament  of  the  ovary 
3.3 


VOL.  II. 


274 


ORGANS  OF  GENERATION,  &c. 


whicli  is  posteriorly,  and  of  that  of  the  round  ligament 
which  is  anteriorly. 

The  mucous  membrane  is  similar  to  that  of  the  vagina. 
It  is  covered  with  fine  villosities,  and,  towards  the  neck, 
presents  very  numerous  orifices  of  mucous  crypts,  some  of 
which  assume  the  form  of  transparent  vesicles. 

The  lu'oper  tissue  of  the  uterus  is  dense,  elastic,  and 
traversed  by  a great  number  of  blood  vessels.  Althougluit 
is  impossible  to  describe  the  exact  disposition  of  its  fibres, 
as  its  structure  is  inextricable  in  the  ordinary  state,  yet 
I entertain  no  doubt  of  its  muscularity.  In  its  impregna- 
ted state,  or  immediately  after  parturition,  its  muscular 
fibres  are  very  apparent  in  dissection.  Sir  C.  Bell  has 
stated  that  the  fibres  of  one  order,  which  cover  the  upper 
segment  of  the  gravid  uterus,  arise  from  the  round 
ligaments,  and,  regularly  diverging,  spread  themselves 
over  the  fundus,  until  they  unite  and  form  the  exterior 
stratum  of  the  proper  tissue  of  the  uterus.  On  the 
outer  surface  and  lateral  parts,  other  muscular  fibres  have 
an  appearance  of  irregularity  among  the  larger  blood 
vessels ; but  they  are  so  disposed  that  they  are  well 
calculated  to  compress  the  vessels,  whenever  the  uterus 
is  excited  to  contraction.  Those  who  have  the  oppor- 
tunity of  examining  the  gravid  uterus  in  its  recent  state, 
will  feel  convinced,  that  it  is  distinctly  and  powerfully 
muscular;  but  the  course  of  the  interior  fibres  are  less 
easily  described  than  we  might  imagine.  This  is  owing 
to  the  intricate  interweaving  of  the  fibres  with  each  other ; 
an  intertexture,  however,  which  gradually  increases  the 
extent  of  their  power  in  diminishing  the  cavity  of  the 
uterus.  After  making  sections  of  the  substance  of  the 
womb  in  ditferent  directions,  says  the  eminent  anatomist 
just  mentioned,  “ I have  no  hesitation  in  saying  that, 
towards  the  fundus,  the  circular  fibres  prevail ; that,  to- 
ward.s  the  orifice,  the  longitudinal  fibres  are  most  appa- 


IN  THE  FEMALE. 


275 


rent ; and  that,  on  the  whole,  the  general  course  of  the 
muscular  fasciculi  is  from  the  fundus  towards  the  orifice.” 
This  prevalence  of  longitudinal  fibres  is  undoubtedly  a pro- 
vision for  diminishing  the  length  of  the  uterus,  by  drawing 
one  extreme  towards  the  other.  At  the  same  time,  such 
an  arrangement  of  the  fibres,  by  their  action,  m.ust  dilate 
the  orifice. 

The  inner  surface  of  the  fundus  consists  of  two  sets  of 
fibres,  running  in  concentric  circles  round  the  orifices  of 
the  Fallopian  tubes  ; these  circles,  at  their  circumference, 
unite  and  produce  an  intricate  tissue.  There  are  other 
strata  of  fibres  commencing  at  the  centre  of  the  last  mus- 
cular fasciculi,  and,  having  a course  at  first  circular,  then 
descend  in  broad  irregular  bands  towards  the  orifice  of  the 
uterus. 

The  arteries  of  the  uterus  are  derived  from  the  sper- 
matic and  hypogastric ; their  principal  branches  are  very 
flexuous,  and  unite  frequently  together  beneath  the  peri- 
tonaeum. Its  veins  follow  the  same  course,  but  are  still 
more  tortuous,  and  form  cavities  in  its  parietes,  which  be- 
come so  large,  during  gestation,  as  to  obtain  the  term  of 
uterine  sinuses. 

When  the  uterus  is  contracted,  the  blood  vessels  are 
invisible,  but,  during  pregnancy,  they  are  so  large  and 
distinct,  that  the  orifices  of  some  of  them,  when  divided, 
will  admit  the  end  of  the  little  finger.  This  fact,  then,  of 
the  natural  closing  of  the  vessels  by  uterine  contraction, 
leads  us  to  contemplate  this  organ  as  admirably  construct- 
ed for  the  reception  of  the  ovum,  the  growth  of  the  fcetus, 
and  the  expulsion  of  the  placenta  without  dangerous 
haemorrhage. 


276 


ORGANS  OF  GENERATION,  &c. 


THE  BROAD  LIGAMENTS. 

The  broad  ligaments*  are  two  folds  of  the  peritonaeum  ; 
they  form,  with  the  uterus  and  the  upper  part  of  the 
vagina,  a transverse  septum,  which  divides  the  cavity  of 
the  pelvis  into  two  parts.  These  ligaments  are  continuous 
by  the  inner  edge,  with  the  peritonaeum  which  invests  the 
two  surfaces  of  the  uterus,  and  are  externally  expanded 
upon  the  sides  of  the  excavation  of  the  pelvis.  They  are 
formed  of  two  peritonseal  laminae,  the  interval  of  which 
contains  cellular  tissue  ; and  superiorly  on  each  side,  the 
Fallopian  tubes ; beneath  and  anteriorly,  the  round  liga- 
ments ; and  posteriorly,  the  ovaries.  The  tubes  occupy  the 
free  edge  of  the  ligament ; the  other  two  organs  raise  its 
surface  and  form  two  smaller  foldings. 


THE  ROUND  LIGAMENTS. 

The  round  ligaments  are  two  long  and  slender  cords, 
commencing  immediately  before  and  below  the  Fallopian 
tubes,  near  the  angles  of  the  uterus,  from  which  they  de- 
scend in  the  broad  ligaments,  and,  diminishing  a little  in 
their  course,  direct  themselves  towards  the  internal  ingui- 
nal ring,  pass  through  it,  and  terminate  by  expanding  in 
the  cellular  tissue  of  the  pudendum. 

Their  structure  is  dense  and  fibrous,  with  an  interposed 
cellular  tissue  and  an  evident  vascularity. 


THE  FALLOPIAN,  OR  UTERINE  TUBES. 

The  Fallopian  tubes,  formerly  very  well  named  the  ovi~ 


* Ligamcnta  lata,  tenncd  sometimes  uhe  vcspcrtilionis. 


m THE  FEMALE. 


.277 


ducts,  are  two  canals  placed  at  the  superior  edge,  and  in  the 
duplicature  of  the  broad  ligaments.  They  are  about  four 
or  five  inches  in  length,  and  extended  from  the  upper  an- 
gles of  the  cavity  of  the  uterus,  to  near  the  side  of  the 
upper  diameter  of  the  pelvis.  In  the  inward  half  of  their 
length  they  are  small  and  straight ; afterwards  these  tubes 
become  larger  and  more  flexuous,  and  terminate  in  a wide 
floating  fringed  extremity,  called  fimbria. 

The  cavities  of  the  Fallopian  tubes  are  very  small,  in- 
deed scarcely  admitting  the  entrance  of  a bristle ; they 
gradually  become  larger  as  they  approach  the  sides  of  the 
pelvis  ; near  their  outer  extremity  they  are  considerably 
dilated,  but  are  afterwards  suddenly  contracted,  and  ter- 
minate by  an  opening  of  sufficient  size  to  admit  the  point 
of  a writing  quill. 

These  tubes  are  lined  by  a very  thin  mucous  membrane, 
of  a florid  color,  slightly  villous,  and  presenting  several 
longitudinal  plicce.  No  mucous  follicles  have  hitherto  been 
discovered  in  them. 

Externally,  these  organs  are  formed  by  a layer  of  spongy 
and  erectile  tissue,  similar  to  that  of  the  urethra,  and,  as 
before  noticed,  invested  by  the  peritonEeum. 


THE  OVARIES. 

The  ovaries,  anciently  termed  testes  muliehres,  are  two 
compressed  oval  bodies  placed  in  the  substance  of  the 
broad  ligament ; they  are  of  a pale  red  color,  and  some- 
what irregular  at  their  surface.  Their  outer  extremity  is 
attached  to  one  of  the  fimbriae  of  the  Fallopian  tubes  ; the 
inner  is  connected  to  the  uterus  by  a small  filamentous 
cord,  about  an  inch  and  a half  long,  called  the  ligament  o f 
the  ovary. 

Each  ovary  is  enveloped  in  a dense  cellular  membrane, 


278 


ORGANS  OF  GENERATION,  &c. 


which  is  prolonged  into  the  parenchyma  of  the  organ,  the 
texture  of  wliich  is  composed  of  a loose  and  spongy  sub- 
stance. When  minutely  examined  we  perceive  cellular 
and  vascular  lobules,  of  a gray  color,  filled  with  fluid.  In 
the  midst  of  these  lobules  we  find  from  fifteen  to  twenty 
transparent  small  vesicles,  called  ova ; these  are  formed  by 
a very  delicate  mend)rane  filled  with  an  albuminous  fluid. 

The  ova  difl'er  in  the  same  ovarium  from  the  size  of  a 
mustard  seed  to  that  of  a pea,  and  the  largest  are  com- 
monly situated  nearest  the  surface. 

In  the  prime  of  life  the  ovaria  are  large  and  uniform  at 
their  surface  ; but  in  females  advanced  in  life  they  become 
small,  unequal,  and  irregularly  formed  ; and  in  those  who 
have  borne  many  children  a similar  irregularity  is  apparent. 

The  ovaria  are  intended  for  the  nourishment  of  the  ova, 
which  contain  the  embryo  or  rudiments  of  the  foetus. 


IN  THE  FEMALE. 


279 


Fig.  91. 


Fig.  91,  exhibits  the  vagina,  the  uterus,  and  its  appen- 
dages. 


a,  the  vagina  cut  open,  shewing  on  its  inner  surface  the 
rugae  and  carunculse. 

b,  the  uterus. 

c,  c,  the  broad  ligaments. 

d,  d,  the  round  ligaments. 

e,  e,  the  Fallopian  tubes. 

/,/,  the  external  opening  of  those  tubes  with  their  fim- 
briae. 


g,  g,  the  ovaria. 


‘280 


ORGANS  OF  GENERATION,  &c. 


THE  GRAVID  UTERUS. 

When  the  ovum  has  been  conveyed  through  the  Fallopian 
tube,  from  its  receptacle,  into  the  cavity  of  the  uterus, 
conception  has  taken  place.  Do  the  rudiments  of  the 
foBtus  proceed  from  the  male  or  from  the  female  ? We 
may  pass  over  the  theories  of  the  ancients  and  moderns  on 
generation  ; at  best  they  are  but  “brilliant  reveries  which 
overload  the  mind  of  the  student,  and  do  more  injury  than 
is  generally  supposed  to  the  progress  of  science.”*  All 
that  physiologists  have  discovered,  as  it  regards  fecunda- 
tion, is,  that  the  part  of  the  male,  in  the  act  of  reproduc- 
tion, is  to  deposit  the  semen  in  the  vagina  at  a greater  or 
less  distance  from  the  orifice  of  the  uterus.  The  function 
which  the  female  discharges  is  more  obscure.  The  uterus, 
at  impregnation,  is  supposed  to  attract  the  semen  and  di- 
rect it  to  the  ovarium  by  means  of  one  of  the  Fallopian 
lubes,  whose  fimbriated  extremity  closely  embraces  that 
organ. 

The  contact  of  the  semen  occasions  the  rupture  and  de- 
livery of  one  of  the  ova,  and  the  fluid  that  passes  from  it, 
or  the  ovum  itself  passes  into  the  uterus,  where  the  new 
individual  is  to  be  developed. 

The  time  which  intervenes  between  the  instant  of  fecun- 
dation and  the  delivery  of  the  child,  is  called  uterogesiation, 
or  pregnancy ; it  is  generally  nine  calendar  months  or 
forty  weeks. 

When  the  ovum  has  arrived  in  the  cavity  of  the  uterus, 
it  closely  unites  with  the  interior  of  this  organ  ; here  it  re- 
ceives the  materials  necessary  for  its  growth,  and  acquires, 
by  degrees,  a considerable  volume:  the  uterus  yields  to  this 
augmentation,  and  consequently,  changes  its  form  and  po- 
sition. 


* MAOENIJtR. 


IN  THE  FEMALE. 


281 


During  the  first  three  months  of  pregnancy,  the  develope- 
ment  of  the  uterus  is  inconsiderable,  and  takes  place  in 
the  hollow  of  the  pelvis  ; but,  in  the  fourth,  as  the  organ 
becomes  larger,  this  cavity  will  no  longer  contain  it,  and  it 
rises  into  the  hypogastrium.  The  uterus  continues  to  in- 
crease in  all  directions  until  the  eighth  month,  when  it  oc- 
cupies a large  space  in  the  abdomen,  compresses  and  dis- 
places the  surrounding  organs,  and  crowds  the  intestines 
into  the  lumbar  and  iliac  regions,  and  its  fundus  reaches 
the  epigastric  region.  After  this  period  the  fundus  recedes 
towards  the  umbilicus. 

The  cervix  uteri  becomes  softer  and  wider  about  the 
fourth  month,  and  afterwards  diminishes  in  length,  and  is 
so  expanded  as  to  entirely  disappear  ; at  the  seventh  month 
the  uterus  has  an  ovoid  form,  and  its  volume  is  twelve 
times  larger  than  in  its  unimpregnated  state. 

The  appendages  of  the  uterus  are  also  considerably  al- 
tered in  relation  to  the  adjoining  part;  the  lamina  of  the 
peritonceal  folds,  that  form  the  broad  ligaments,  separate 
and  assist  in  forming  a covering  to  the  uterus.  The  vagina 
is  increased  in  length.  The  ovaria,  retained  by  their  ves- 
sels, do  not  ascend  with  the  fundus  uteri ; but,  with  the 
Fallopian  tubes,  are  now  situated  on  its  lateral  parts. 
The  round  ligaments  are  thicker,  more  vascular,  and  yield 
to  its  elevation. 

The  abdominal  parietes  suffer  very  considerable  disten- 
tion, so  that  the  umbilical  depression  is  entirely  obliterated. 

As  the  magnitude  of  the  uterus  increases,  it  assumes  a 
cellular  appearance  of  a deep  red  color,  and  its  fibres  be- 
come more  evident.  On  the  exterior,  they  take  a direction 
I have  already  described  ; but  the  internal  fibres  of  the 
uterine  tissue  have  some  analogy  with  those  of  the  heart 
and  the  tongue,  in  presenting  an  inextricable  interlace- 
ment, where  no  regular  arrangement  can  be  distinguished. 
Its  interior  surface  contains,  immediately  after  impregna- 

voL.  II.  36 


282 


ORGANS  OF  GENERATION,  &c. 


tion,  an  albuminous  layer,  which  increases  with  the  organ 
in  the  earlier  periods  of  pregnancy,  and  subsequently  be- 
comes a vascular  membrane.  Dr.  Hunter,  who  first  care- 
fully described  it,  called  it  the  decidua,  from  its  being  ulti- 
mately cast  olf  from  the  uterus.  It  is  supposed  to  favor 
the  adherence  of  the  ovum  to  the  internal  surface  of  the 
uterus. 

The  arteries  are  now  observed  to  have  very  frequent 
communications,  and  in  their  course  are  remarkably  en- 
larged and  convoluted.  But  the  veins  are  much  larger 
than  the  arteries,  their  diameter,  as  we  have  stated,  being 
such  as  to  distinguish  them  as  sinuses  ; these  materially 
contribute  to  form  the  great  bulk  of  the  uterine  parietes. 
The  lymphatic  vessels  also  become  very  voluminous.  It 
is  evident  that  the  quantity  of  blood  that  traverses  the 
uterus,  is  in  relation  to  the  changes  it  has  undergone,  and 
4he  new  functions  it  is  required  to  fulfil. 

DEVELOPEMENT  OF  THE  OVUM  IN  THE  UTERUS. 

The  ovum  is  quite  unattached  during  the  first  period 
of  its  abode  in  the  uterus  ; but  in  the  course  of  the 
second  month  its  dimensions  have  increased  ; it  becomes 
covered  with  filaments  which  ramify  in  the  manner  of 
blood  vessels,  and  are  implanted  into  the  decidua.  About 
the  third  month  they  exist  on  one  side  of  the  ovum  only, 
and  are  connected  with  that  part  of  the  deciduous  mem- 
brane, forming  the  placenta.  The  ovum  in  the  remainder 
of  its  surface,  presents  a flocculent  layer,  sometimes 
termed  the  decidua  rejlexa. 

The  ovum,  at  the  termination  of  the  second  month,  is 
of  the  size  of  an  egg  ; and,  when  there  has  been  an  abor- 
tion, we  trace  very  distinctly  the  membranes  which  inclose 
the  embryo,  viz.  : — 


IN  THE  FEMALE. 


283 


MEMBRANES  WHICH  INCLOSE  THE  FCETUS. 

1st.  The  amnion,  a membrane  placed  next  to  and  di- 
rectly enveloping  the  foetus  ; it  is  very  thin  and  pellucid, 
but  firm  in  texture,  and  not  easily  torn ; it  covers  the  pla- 
centa, is  reflected  over  the  umbilical  cord,  and  terminates 
at  the  umbilicus.  It  is  united  to  the  chorion  by  the  inter- 
vention of  a gelatinous  substance. 

2d.  The  chorion,  a flocculent,  spongy  membrane,  com- 
pletely investing  the  ovum,  and  lining  the  uterus  ; this 
membrane  is  considerably  thicker  in  the  earlier  than  in  the 
more  advanced  stages  of  utero-gestation  ; it  then  becomes 
transparent,  and  is  united  to  the  amnion  in  the  manner  just 
mentioned. 

3d.  The  decidua,  which  may  be  properly  considered  as 
the  membrane  lining  the  uterine  cavity ; it  is  much  thicker 
than  either  of  the  other  membranes,  but  its  texture  is  less 
dense,  and  it  is  very  easily  torn.  It  is  placed  between  the 
proper  membranes  of  the  impregnated  ovum  and  the  ute- 
rine surface.  The  decidua  is  only  formed  by  the  uterus 
during  impregnation  : its  formation  commences  with  con- 
ception. At  first  it  is  a mere  fluid  secretion,  which  after- 
wards assumes  a flocculent  membranous  appearance ; it 
increases  in  extension  and  thickness  in  proportion  to  the 
evolution  of  the  uterus.  It  is  adherent  to  the  inner  sur- 
face of  that  organ,  and  is  extended  over  the  chorion,  to 
which  it  is  connected  by  a vascular  attachment ; it  is  always 
thrown  off  after  parturition. 

The  decidua  serves  as  a capillary  system,  intended  to  be 
the  medium  of  communication  between  the  blood  vessels 
of  the  mother  and  the  foetus.  The  decidual  vessels  receive 
the  arterial  blood  of  the  former,  and  these  vessels  are  ex- 
tended over  a very  considerable  surface  of  tubular  struc- 
ture, w'hich,  in  its  distribution,  is  in  apposition  with  the 


284  ORGANS  OF  GENERATION,  &c. 

infinite  ramifications  of  the  umbilico-placental  vessels  at 
innumerable  points;  and  by  these  means  the  required 
changes  in  the  blood  of  the  foetus  are  as  effectually  pro- 
duced, as  the  changes  called  for  in  the  pulmonic  blood  are 
produced  by  the  peculiar  arrangement  of  the  pulmonary 
apparatus.  When  the  arterial  blood  of  the  mother  has 
produced  the  desired  effect  on  that  of  the  foetus,  it  is  re- 
turned by  the  decidual  veins  to  the  surface  of  the  uterus, 
where  it  enters  into  the  general  venous  system  of  the 
mother. 


LiqUOR  AMNII. 

The  membranes  contain  a quantity  of  fluid  termed  liquor 
amnii,  which  is  augmented  in  proportion  to  the  advanced 
state  of  gestation.  According  to  Professor  VAuquELiN,  it 
is  formed  of  water,  albumen,  soda,  muriate  of  soda,  and 
phosphate  of  lime.  The  uses  of  this  fluid  are  to  afford  a 
soft  medium  for  the  residence  of  the  foetus,  to  which  it 
allows  a free  motion,  and  protects  its  delicate  structure 
from  any  external  injury,  to  which,  from  the  exertions  of 
the  mother,  it  might  occasionally  be  liable.  The  waters  of 
the  amnios  are  also  useful  in  parturition,  by  dilating  the 
orifice  of  the  uterus,  and  lubricating  the  external  organs  of 
generation. 


THE  PLACENTA.  (Fig.  95.) 

The  'placenta  is  a rounded,  oblong  and  soft  mass,  by 
means  of  which  the  ovum  is  attached  most  intimately  to 
the  uterus.  This  body  is  generally  about  eight  inches  in 
its  greatest  diameter,  six  in  the  smallest,  and  one  thick  ; 
but  it  gradually  becomes  thinner  towards  the  circumfer- 


IN  THE  FEMALE. 


285 


ence.  Its  thickest  portion  is  where  the  umbilical  cord  is 
connected  to  it. 

This  organ  forms  a most  important  part  of  the  uterine 
contents  : its  structure  is  entirely  vascular,  with  the  simple 
interpositon  of  cellular  membrane ; so  that  in  its  general 
substance,  when  excluded  from  the  uterus,  it  is  found  to 
consist  of  the  different  branches  and  divarications  of  the 
umbilical  arteries  and  veins,  united  together  by  a fine  cellu- 
lar tissue.  The  whole  of  this  organ  is  strictly  foetal : it 
contains  within  its  structure  cells  or  sinuses  of  consider- 
able extent,  into  which  the  uterine  vessels  at  the  point  of 
contact  open,  and  over  which  their  contents  are  circulated 
and  returned,  as  long  as  the  organ  is  attached  to  the 
uterine  surface.  This  cellular  part  of  the  placenta  has 
acquired  the  name  of  the  maternal  portion. 

The  placenta  possesses  within  its  structure  the  means  of 
two  distinct  circulations,  each  of  which  is  continued 
through  distinct  channels : the  one  passes  the  blood  from 
the  uterine  parietes  into  the  placental  cells,  and  returns  it 
back  to  the  uterus  : this  is  properly  the  maternal  circula- 
tion, and  continues  as  long  as  the  placenta  is  attached  to 
the  uterine  surface.  The  other  conveys  the  blood  of  the 
child  from  its  body,  and  back  again  through  the  numerous 
ramifications  of  the  umbilical  vessels  : this  forms  the  foetal 
circulation.  These  two  circulations  are  so  completely 
separate  and  distinct,  that  they  do  not  interfere  with  each 
other  : each  is  entirely  unconnected  with,  and  independent 
of  the  other ; as  far  as  positive  communications  of  vessels 
are  concerned,  the  foetal  vessels  do  not  pass  their  contents 
into  the  placental  cells,  neither  do  the  uterine  vessels,  com- 
municating with  the  placental  cells,  pass  their  contents 
into  the  foetal  structure.  There  is  no  mixture  of  foetal  and 
maternal  blood  ; and  no  circulating  communication,  direct 
or  indirect,  exists  between  the  foetus,  from  apposition  at 


286  ORGANS  OF  GENERATION,  &c. 

the  part  to  which  the  placenta  is  attached  and  through  its 
medium. 

A satisfactory  notion,  therefore,  of  the  mode  in  which 
tlie  principles  of  life  are  communicated  to  the  embryo,  of 
the  materials  from  which  it  is  evolved,  or  the  manner  in 
which  the  placenta  is  appropriated  to  its  service,  has  hither- 
to never  been  obtained  ; yet  there  are  some  points  which 
are  obvious  and  acknowledged.  The  following  are  facts 
which  almost  admit  of  demonstration. 

1st.  When  conception  has  taken  place,  a principle  of 
internal  action  and  growth  is  established  in  the  uterus,  by 
which  its  parietes  are  enlarged  in  every  direction,  and  its 
cavity  is  increased  in  capacity.  2d.  One  of  the  immediate 
effects  of  this  primary  change,  is  a secretion  furnished  by 
the  vessels  of  its  internal  surface,  which  at  first  becomes 
the  connecting  medium  between  the  mother  and  the  em- 
bryo, and  afterwards  the  deciduous  membrane.  3d.  When 
the  ovum  is  received  into  the  uterine  cavity,  it  attaches 
itself  to  a point  to  which  the  uterine  vessels  are  more  par- 
ticularly directed,  and  at  which  also  certain  vessels  from 
itself  are  implanted.  4th.  These  several  parts  increase  in 
size  until  the  rudiments  of  the  placenta  are  formed,  and 
there  is  a regular  increase  of  its  whole  substance,  propor- 
tionate to  the  demand  of  the  embryo  for  nourishment,  and 
to  the  uterine  growth. 

The  placenta  adheres  to  the  uterus  by  a simple  apposi- 
tion of  parts,  and  by  that  peculiar  connection  of  vascular 
circulation  which  subsists  between  the  uterine  vessels  at 
the  point  of  contact,  and  the  placental  cells.  The  blood 
vessels  of  the  gravid  uterus  run  through  its  parietes  in  a 
serpentine  direction : and,  in  the  distribution  of  blood,  the 
venous  system  possesses  a larger  diameter  than  the  arte- 
rial. Though  the  placenta  is  in  apposition  in  so  simple  a 
manner  with  the  uterine  surface,  it  is  not  in  immediate 
contact  with  it,  the  deciduous  membrane  being  interposed 


IN  THE  FEMALE. 


becomes  the  bond  of  union  between  the  two,  except  at 
those  points  at  which  the  uterine  vessels  pass  their  blood 
into  the  placental  cells. 

The  placenta  is  commonly  attached  to  the  fundus  uteri, 
but  there  is  no  part  of  its  internal  surface  at  which  this 
organ  may  not  occasionally  be  found. 


OFFICE  OF  THE  PLACENTA. 

The  office  of  the  placenta  is  strictly  foetal ; it  is  an  organ 
originally  formed  for  and  appropriated  to  the  service  of  the 
foetus,  and  is  the  only  communication  between  the  mother 
and  her  infant ; it  is  the  sole  medium  through  which  the 
principles  of  nourishment  and  growth  can  be  conveyed 
from  the  one  to  the  other.  The  foetal  blood  distributed 
by  the  branches  of  the  umbilical  arteries  over  the  placental 
mass,  receives,  as  before  stated,  from  the  decidual  appara- 
tus, certain  additions  in  that  circulation  necessary  to  foetal 
life;  and  is  returned  to  the  child  by  the  umbilical  vein, 
replete  with  that  vitality  which  it  has  acquired  in  its  passage 
through  the  placenta.  The  blood  of  the  child  under  this 
state  of  improvement,  if  I may  be  allowed  the  expression, 
may  be  compared  to  that  of  the  adult  after  its  passage 
through  the  lungs.  Thus  if  interruption  to  the  return  of 
the  foetal  blood,  from  the  placental  circulation,  occurs  from 
any  cause,  the  life  of  the  foetus  is  as  certainly  destroyed,  as 
if  the  free  passage  of  the  air  into  the  lungs  was  prevented 
during  breathing  life. 


FUNIS  UMBILICALIS. 

The  Junis  umbilicalis  is  that  vascular  cord  which,  passing 
from  the  placenta  to  the  umbilicus  of  the  child,  maintains 


288 


ORGANS  OF  GENERATION,  &c. 


the  communication  between  the  foetus  and  the  placenta. 
Its  length  is  almost  two  feet ; it  is  composed  of  two  arteries 
and  one  vein,  the  spaces  between  which  are  occupied  by  a 
gelatinous  substance,  contained  in  cells,  which  serves  to 
prevent  any  obstruction  to  the  current  of  the  blood  from 
accidental  compression.  The  funis  is  covered  by  the 
amnion,  or  inner  membrane  of  the  ovum,  and  the  vein  is 
sufficiently  large  to  reconduct  to  the  fcetus  the  whole  or  an 
equal  quantity  of  blood  to  that  which  is  conveyed  from  the 
two  arteries  from  it  to  the  placenta.  The  arteries  twist 
round  the  vein  in  a beautiful  spiral  manner. 

The  funis  seems  to  be  the  production  of  the  placenta, 
for,  soon  after  the  birth  of  the  child,  there  is  a spontaneous 
separation  of  the  funis  at  the  umbilicus. 

UMBILICAL  VESICLE. 

In  the  first  months  of  gestation,  a vesicle  is  found  in  the 
body  of  the  umbilical  cord,  between  the  chorion  and 
amnion,  near  the  umbilicus  : it  receives  small  vessels  from 
a prolongation  of  the  mesenteric  artery  and  the  meseraic 
vein.  It  contains  a yellowish  fluid,  the  uses  of  which  are 
not  known  : after  the  fourth  month  it  becomes  absorbed. 

Sometimes  this  vesicle  has  been  observed,  at  the  full 
period  of  gestation,  placed  near  the  placenta  ; it  is  connect- 
ed, as  before  stated,  by  vessels  to  the  intestines,  at  the 
termination  of  the  ilium  or  coecum.  At  the  lower  end  of 
the  anal  intestines  there  projects  another  vesicle  or  sac  to 
which  the  name  of  allantoid  has  been  given  ; it  exists  in 
all  the  mammalia,  and  in  the  human  embryo  it  appears 
about  the  fourth  week,  but  by  the  third  month  it  disap- 
pears : the  use  of  this  vesicle  also  is  unknown. 


fN  THE  EEMALE. 


289 


THE  BREASTS  (MAMMic). 

The  breasts  form  part  of  the  generative  organs  ; before 
the  age  of  puberty  they  are  small  and  flat,  but  in  the  adult 
and  well  formed  female,  they  present  two  hemispheres,  or 
conical  eminences,  covered  by  a smooth  semitransparent 
skin,  softer  and  less  colored  than  that  of  the  other  parts  of 
the  body. 

Near  the  centre  of  each  breast  the  color  of  the  skin 
abruptly  changes,  and  assumes  a rosy  tint  in  young  females, 
and  a reddish  brown  one  in  women  who  are  pregnant  or 
have  suckled  several  children.  This  deep  colored  circle  is 
called  the  areola  of  the  nipple. 

The  nipple  (papilla ) rises  in  the  middle  of  the  areola  ; 
and  is  always  of  the  same  color : it  is  susceptible  of  a kind 
of  erection. 

The  skin  of  the  areola  and  nipple  has  a wrinkled  ap- 
pearance, and  is  remarkable  for  its  tenuity  : it  presents  a 
number  of  sebaceous  glands,  which  furnish  an  unctuous 
fluid  calculated  to  protect  these  parts  against  the  action  of 
the  saliva  of  the  child.  We  observe  upon  the  surface  of 
the  nipple  numerous  very  fine  papillae,  in  which  are  the 
orifices  of  the  lactiferous  ducts. 


ORGANIZATION  OF  THE  BREASTS. 

Beneath  the  skin  there  is  a layer  of  adipose  tissue,  and 
it  is  chiefly  to  this  that  the  breast  owes  its  size  and  form. 

The  mammary  gland  is  situated  behind  the  adipose  tissue, 
and  before  the  great  pectoral  muscle;  it  has  a convex  and 
uneven  surface,  and  an  irregularly  circumscribed  base. 
Adipose  tissue  is  also  found  in  the  intervals  which  intersect 
the  lobules. 


VOL.  II. 


37 


290 


ORGANS  OF  GENERATION,  &c. 


The  tissue  of  the  mammary  gland  consists  of  an  assem- 
blage of  lobes  of  different  sizes,  closely  connected  with 
each  other  by  a dense  cellular  tissue.  Each  of  these  lobes 
is  composed  of  several  lobules,  which  are  obviously  form- 
ed of  granulations  of  a pink  color,  and  the  size  of  a poppy 
seed.  If  we  further  examine  these  small  granules,  w^e  find 
that  they  consist  of  a number  of  minute  vesicles  and  an 
organized  tissue. 


Fig.  f)2. 


Fig.  92,  represents  one  of  the  mammae  dissected  from 
the  pectoralis  major  muscle. 

a,  the  skin. 

b,  the  same  dissected  and  refiected  to  show 

c,  cl,  the  mammary  glands ; 

e,  the  origins  of  the  lactiferous  ducts,  and 

f,  the  nipple. 


IN  THE  FE3IALE. 


291 


The  lactiferous  ducts  arise  from  the  granulations  of  the 
vesicles  just  mentioned  ; they  commence  in  capillary  tubes, 
termed  the  tuhuli  Jactiferi,  which  uniting  into  branches, 
collect  into  trunks,  and  proceed  towards  the  centre  of  the 
gland.  Those  of  the  different  lobes  do  not  communicate 
with  the  others,  so  that  there  are  as  many  series  of  vessels 
as  there  are  lobes  in  the  gland ; but  they  all  terminate  in 
fifteen  or  sixteen  sinuses  in  the  centre  of  the  nipple,  and 
open  separately  on  its  surface. 

When  the  nipple  is  contracted,  the  lactiferous  canals 
are  compressed,  and  the  milk  usually  ceases  to  flow  ; but 
by  the  sucking  of  the  child  a vacuum  is  produced,  into 
which  the  milk  very  readily  escapes  from  the  orifices  of 
these  canals. 


OFFICE  OF  THE  MAMM^. 

The  child  continues  for  some  time  after  birth,  depend- 
ent upon  the  maternal  system  for  its  nourishment,  and  a 
food  is  provided  which  alone  is  suitable  to  the  delicacy  of 
the  infantine  organs.  This  food  is  the  milk  ; it  is  furnish- 
ed by  the  mammae  until  the  termination  of  nursing,  or  con- 
tinues until  the  end  of  the  second  year. 

The  color,  odor,  and  taste  of  milk  is  known  to  every 
one  ; it  is  one  of  the  most  azotised  glandular  liquids  : but 
there  is  no  fluid  secretion  more  readily  modified  by  the 
diet,  by  the  time  after  delivery,  by  medicines,  or  by  affec- 
tions of  the  mind.  On  the  average,  the  milk  of  a healthy 
person,  according  to  Berzelius,  is  composed  of  milk,  pro- 
perly so  called,  and  cream. 


292  ORGANS  OF  GENERATION,  &c. 

Milk  contains  : 

Water, 928-75 

Cheese  with  a trace  of  sugar,  28'00 

Sugar  of  milk, 35‘00 

Muriate  of  potass,  . . . . 1-70 

Phospliate  of  potass,  . . . 0-25 

Lactic  acid,  acetate  of  potass,  and 

lactate  of  iron,  ....  6-00 

Phosphate  of  lime,  ....  0-30 

Cream  contains  : 

Butter, 4-5 

Cheese, 3’5 

Whey, 92-0 

In  this  last  4-4  of  sugar  of  milk,  and  salt  is  found. 


ART.  XV. 


THE  FCETUS. 


PECULIARITIES  OF  THE  FffiTUS. 

The  osseous  system  of  the  foetus  is  found  in  a very  dif- 
ferent state  to  that  of  the  adult ; the  foetal  bones  are  soft 
and  yielding.  The  situations  of  many  of  them  are  occu- 
pied by  mere  cartilage ; indeed,  all  the  bones,  prior  to 
their  assuming  a regular  form,  are  of  a cartilaginous  con- 
sistence, and  the  parts  termed  epiphyses,  that  is,  the  ex- 
tremities of  long  bones,  up  to  the  period  of  birth  have 
entirely  this  character.  Most  of  the  cylindrical  and  some 
of  the  flat  and  irregular  bones,  are  formed  of  several  dis- 
tinct parts,  each  of  which  has  its  centre  of  ossification,  and 
these  parts  can  be  easily  separated  by  boiling,  or  by  macer- 
ation in  water. 

In  the  chemical  composition  of  the  bones  of  the  fcetus, 
there  is  a smaller  proportion  of  the  phosphate  of  lime, 
than  in  the  adult.  The  foetal  bones  are  also  more  uniform 
on  their  surface,  as  they  are  not  marked  by  the  action  of 
muscles  ; their  cavities  are  filled  with  gelatin  instead  of 
marrow. 

The  head  is  large  in  proportion  to  the  body,  and  in  the  ’ 
bones  of  the  cranium  we  may  observe  very  distinctly  their 


294 


THE  FCETUS. 


fibrous  structure.  In  a foetus  about  three  months  after 
conception,  the  commencement  of  ossification  in  each 
bone  is  like  a fine  irregular  net-work,  in  the  centre  of 
which,  the  fibres  are  more  closely  connected  than  at  its 
circumference.  In  viewing  the  flat  bones  of  the  foetus,  at 
a more  advanced  period,  the  osseous  particles  are  observed 
to  have  a radiated  appearance  ; as  the  foetus,  however, 
attains  a larger  growth,  the  osseous  fibres  increase  in  num- 
ber, until  a lamina  is  produced  ; and  in  the  progress  of 
ossification,  other  lamina3  are  added,  and  a succession  of 
these  laminae  form  the  more  solid  fabric  of  the  bone. 

Fig.  93. 


a,  the  os  frontis,  which  at  early  life  consists  of  two  pieces 
divided  by  a vertical  suture  termed  the  frontal. 

I,  the  anterior  fontanel. 

In  the  child  the  cranium  bears  a large  proportion  to  the 
face,  owing  to  the  size  of  the  brain,  the  absence  of  the 
sinuses  in  the  forehead,  and  of  the  teeth  in  the  gums  ; 
and  the  younger  the  embryo,  the  greater  is  the  dispro- 


THE  FCETUS. 


295 


portion  between  the  head  and  the  rest  of  the  body.  Be- 
tween the  frontal  and  parietal  bones,  is  the  space  called 
anterior  hregma,  or  fontanel,  (Fig.  93,  5,)  formed  by  an 
irregular  quadrangular  membranous  substance,  which  com- 
monly disappears  before  the  child  attains  the  age  of  two 
years,  the  margins  of  the  bones  being  then  united.  Be- 
tween the  middle  of  the  lambdoidal  and  posterior  extreme 
of  the  sagittal  suture,  a similar  membrane  of  a triangular 
form  is  also  frequently  observed,  termed  the  posterior 
hregma,  or  fontanel,  (Fig.  94,  c,)  but  in  a well  formed  head 
it  is  scarcely  to  be  traced. 


a,  the  frontal  suture. 

b,  the  anterior  fontanel. 

c,  the  posterior. 

The  rudiments  of  the  teeth  are  situated  in  canals  in  the 
jaws,  in  sacs  called  the  capsules  of  the  teeth  ; these  con- 
sist of  two  membranes,  containing  a pulpy  matter.  The 


Fig.  94. 


296 


THE  FOETUS. 


inner  membrane,  about  the  sixth  month,  forms  a thin 
layer  of  enamel ; and  at  the  period  of  birth  the  shells  of 
ten  teeth  are  found  in  each  jaw. 

The  fluids  in  the  foetus,  are  proportionally  large  in 
quantity,  and  the  solids  generally  softer  than  in  the  adult. 

The  skin  is  of  a florid  color,  in  consequence  of  a greater 
degree  of  vascularity,  and  is  generally  covered  with  an 
unctuous  substance,  supposed  to  be  secreted  by  the  vessels 
of  the  rete  mucosum. 

Adeps  is  chiefly  found  near  the  surface  of  the  body  ; very 
little  is  formed  in  the  interior  parts  until  later  in  life,  when, 
in  healthy  persons,  it  afterwards  gradually  accumulates  as 
they  advance  to  a certain  age. 

The  brain,  spinal  marrow,  and  nervous  system,  are 
proportionally  large,  but  soft  in  their  texture.  The  vas- 
cular system,  and  glandular  organs  bear  the  same  pro- 
portion. 

The  cornea  of  the  foetal  eye  is  thick  and  prominent. 
The  pupil  is  occupied  by  the  membrana  pujpillaris,  which 
is  attached  to  the  circumference  of  the  inner  margin  of  the 
iris,  and  continues  there  until  the  seventh  month,  when  it 
gradually  disappears  in  consequence  of  being  absorbed. 
This  membrane  is  very  vascular,  and  separates  the  two 
chambers  of  the  eye  from  each  other.  The  only  use  that 
can  be  assigned  to  it  is,  that  it  is  an  organ  of  secretion, 
which  is  requisite  for  the  production  of  the  humours 
during  the  rapid  increase  of  the  globe  of  the  eye.  The 
crystalline  lens  is  almost  spherical,  and  numerous  vessels 
pass  from  the  ciliary  process  to  be  dispersed  upon  its  cap- 
sules. 

The  meatus  auditorius  is  wholly  cartilaginous,  and 
adheres  to  a ring  of  bone  in  which  the  membrana  tympani 
is  placed.  The  meatus  externus,  and  membrana  tympani, 
are  lined  by  a mucous  membrane  which  separates  after 
birth. 


THE  FCETUS. 


297 


In  this  stage  of  existence  certain  glandular  bodies  are 
developed,  the  uses  of  which  are  still  unknown,  but  which 
continue  large  and  vascular  till  towards  puberty,  and  after- 
wards shrink  and  waste.  The  thymus  gland  is  one  of 
these : it  is  situated  in  the  upper  part  of  the  thorax,  be- 
tween the  laminae  of  the  anterior  mediastinum,  and  over 
the  pericardium ; processes  of  this  gland  always  ascend  on 
each  side,  as  far  as  the  neck.  It  abounds  with  a milky 
fluid  ; but  it  has  never  yet  been  observed  to  have  any 
e.xcretory  duct ; nor  has  the  use  of  the  fluid  or  of  the 
gland  yet  been  ascertained.  Part  of  the  thymus  gland 
remains  during  youth,  but  it  usually  disappears  altogether 
in  old  age.  The  supra-renal  capsules  of  the  foetus  are 
large,  when  compared  to  their  diminished  capacity  in  after 
life. 

As  the  lungs  have  not  commenced  their  functions,  their 
appearance  is  extremely  different  from  what  it  is  after 
they  have  been  inflated  by  the  inspiration  of  air : they  are 
proportionally  much  smaller,  their  color  is  darker,  their 
substance  denser,  and  their  specific  gravity  is  so  much 
greater  that  they  sink  in  water. 

The  heart,  in  the  foetus,  is  proportionally  larger  than  in 
the  adult,  and  the  Eustachian  valve  is  more  distinct  ; it  is 
supposed  to  direct  the  current  of  blood,  coming  from  the 
abdomen,  through  the  passage  immediately  to  be  mention- 
ed, existing  in  the  septum  of  the  auricles  : — 

This  opening  is  denominated  the  foramen  ovale  : it  is 
situated  obliquely  in  the  partition  which  separates  the  right 
and  left  auricles ; it  is  nearly  of  the  dimensions  of  the 
orifice  of  the  cava,  and  it  is  bounded  by  a muscular  mar- 
gin, termed  annulus  foraminis.  The  greatest  part  of  the 
blood  which  arrives  from  the  inferior  cava,  is  poured  into 
the  left  auricle,  during  the  diastole  of  the  ventricles.  A 
falciform  valve,  placed  over  the  foramen,  prevents  its  re- 
turn, and  appears  likewise  to  preclude  its  course  into  the 
38 


VOL.  II. 


29B 


THE  fXETUS. 


left  auricle,  during  the  systole  of  the  auricles.  The  blood 
passing  through  the  foramen  ovale  keeps  up  the  balance  of 
the  circulation  between  the  sides  of  the  heart,  till  the  lungs 
are  ready  to  receive  it.  The  foramen  is  then  generally 
soon  obliterated. 

The  pulmonary  artery  divides  into  three  branches  ; the 
right  and  the  left  of  which  proceed  to  the  lungs,  while  the 
middle  one,  termed  ductus  arteriosus,  (Fig.  95,  m,')  which 
is  larger  than  both  the  other  branches,  passes  in  an  oblique 
direction  to  the  beginning  of  the  descending  aorta.  The 
ductus  arteriosus  is  therefore  another  temporary  passage 
for  carrying  a part  of  the  blood  of  the  right  ventricle  into 
the  aorta,  without  passing  the  circuitous  route  through 
the  lungs ; it  thereby  assists  the  foramen  ovale,  in  keeping 
up  the  communication  required  between  each  side  of  the 
heart,  till  the  child  has  breathed  ; and  by  these  means  also 
the  aorta  receives  the  force  of  both  ventricles,  to  move  the 
blood  through  the  umbilical  arteries  ; without  this  joint 
action  it  is  probable  the  blood  would  not  reach  the 
placenta,  and  again  return  to  the  heart. 

According  to  this  dispositon  of  the  circulating  appara- 
tus of  the  foetus,  it  is  evident  that  the  motion  of  the  I 
blood  must  be  different  from  that  in  the  adult.  The  j 
blood  from  the  placenta  passes  through  the  umbilical  vein  | 
as  far  as  the  liver;  then  one  part  of  the  blood  proceeds  j 
into  the  liver  and  the  other  into  the  vena  cava ; from  these 
two  parts  it  arrives  at  the  heart,  and  rushes  into  the  right 
auricle,  by  the  inferior  cava,  and  into  the  left  by  the  fora- 
men ovale.  The  contraction  of  the  auricles  succeeds 
their  dilation,  and  the  blood  is  compressed  into  the  ven- 
tricles ; these  in  their  turn  contract  and  propel  the  blood 
into  the  aorta,  except  a very  small  portion,  which  goes  to 
the  lungs.  By  the  united  influence  of  the  two  ventri- 
cles, the  stream  of  blood  is  forced  through  all  the  divisions 
of  the  aorta,  and  returns  to  the  heart  by  the  venre  | 


THE  FCETUS. 


299 


cavas.  Lastly,  it  is  transmitted  to  the  placenta  by  the 
umbilical  arteries,  and  returns  to  the  foetus  by  the  vein  of 
the  funis. 

The  motions  of  the  heart  in  the  foetus  are  very  rapid  ; 
they  generally  exceed  one  hundred  and  twenty  in  a 
minute  : the  circulation  necessarily  possesses  a proportion- 
ate rapidity. 

The  abdomen  is  proportionally  larger ; and  the  stomach 
is  rounder  than  in  the  adult,  and  commonly  contains  a 
small  quantity  of  gelatinous  matter.  The  omentum  has  a 
very  small  quantity  of  fat  between  its  laminae.  From  the 
remarkable  mode  of  nutrition  of  the  foetus,  it  is  clear  that 
its  alimentary  canal  and  the  chylopoietic  system  must  be 
very  peculiar.  The  valvulae  conniventes  of  the  small  in- 
testine are  scarcely  perceptible.  The  appendix  vermi- 
formis  is  very  large,  and  is  inserted  into  the  extremity  of 
the  colon,  which  at  this  time  does  not  project  to  form  a 
proper  caecum.  The  large  intestine  very  nearly  resembles 
the  small,  its  longitudinal  muscular  bands  being  very  in- 
distinct. The  colon  contains  a blackish  green  feces,  of  a 
viscid  consistence,  termed  meconium,  which  appears  to  be 
a mixture  of  bile  with  secretions  from  the  intestines. 

The  liver  is  so  large  as  to  occupy  both  hypochondriac 
regions,  and  to  extend  some  distance  below  the  margin  of 
the  thorax.  The  gall-bladder  is  filled  with  bile  of  an 
extremely  dark  color. 

The  umbilical  vein  passes  from  the  umbilicus,  in  a 
duplicature  of  the  peritonaeum,  behind  the  recti  muscles, 
to  the  fossa  umbilicalis  of  the  liver,  and  thence  to  the  left 
branch  of  the  vena  portae,  and  transmits  the  blood  from  the 
placenta  to  the  liver.  From  the  umbilical  vein,  where  it 
terminates  in  the  liver,  a branch,  called  ductus  venosus,  (Fig. 
95,  h,)  proceeds  in  a somewhat  waving  direction,  and  joins 
the  left  vena  hepatica,  where  that  vein  enters  the  cava. 
The  ductus  venosus  transports  part  of  the  blood  of  that 


300 


THE  FCETUS. 


vein  directly  to  the  heart,  without  the  intervention  of  the 
hepatic  circulation.  The  reason  for  this  distribution  of  the 
umbilical  vein  is  not  understood. 

The  pancreas  and  other  glandular  organs  are  large  in 
their  relative  dimensions.  The  kidneys  are  formed  of 
lobes,  in  number  nearly  corresponding  with  the  papillae. 

The  pelvis  of  the  foetus  is  commonly  so  small,  that  the 
principal  parts  of  the  organs,  afterwards  situated  in  it,  are 
at  this  time  contained  in  the  cavity  of  the  abdomen.  The 
urinary  bladder  is  of  a long  form,  and  extends  almost  to 
the  umbilicus. 

The  urachus  is  a solid  fibrous  substance  ; it  is  attached 
to  the  fundus  of  the  bladder,  between  the  umbilical 
arteries,  and,  passing  behind  the  linea  alba  to  the  umbili- 
cus, disappears  by  degrees  in  the  umbilical  cord.  In  some 
instances  it  is  hollow  in  a part  or  through  the  whole  of  its 
extent. 

The  common  iliac  arteries  divide,  on  each  side,  into  a 
small  external,  and  a large  internal  branch  : the  umbilical 
arteries  arise  from  the  internal  iliacs,  are  directed  over  the 
sides  of  the  bladder,  attach  themselves  to  the  urachus,  pass 
out  of  the  abdomen  by  the  umbilicus,  and  are  distributed 
to  the  placenta. 

Soon  after  parturition  the  foramen  ovale,  ductus  arte- 
riosus et  venosus,  with  the  umbilical  vein  and  arteries  begin 
to  contract  and  are  in  general  completely  closed,  the  ves- 
sels appearing  like  ligaments  within  a year  after  birth. 

In  the  very  young  male  foetus,  the  testes  are  situated 
in  the  cavity  of  the  abdomen,  over  the  psose  muscles,  and 
a little  below  the  kidneys,  so  that  they  constitute  a part  of 
the  abdominal  organs,  and  in  a similar  manner  with  them, 
are  connected  to  the  body  by  a process  of  peritonaeum, 
which  subsequently  forms  the  tunica  albuginea.  Between 
the  testis  and  scrotum  a fibrous  and  vascular  substance  is 
extended,  called  by  Hunter,  gubernaculum,  which  he  con- 


THE  FCETUS. 


301 


sidered  as  a principal  agent  in  directing  the  course  of  the 
testis  in  its  descent.  This  remarkable  passage  of  the 
testis  from  the  abdomen,  through  the  ring  into  the  scrotum, 
is  limited  to  no  period,  but  it  usually  occurs  about  the  last 
month  of  gestation.  No  satisfactory  explanation  has  ever 
been  offered  as  to  the  cause  of  this  singular  transit  of  an 
important  organ  to  a distant  situation.  It  has  been  ad- 
duced, by  Blumenbach,  as  a striking  illustration  of  a vita 
propria,  without  the  peculiar  influence  of  which,  so  re- 
markable and  unique  a movement,  similar  to  no  other 
function  in  the  system,  cannot  even  be  imagined. 


302 


THE  ECETUS. 


Fig.  95. 


THE  FCETUS. 


303 


Fig.  95,  is  a representation  of  the  manner  in  which  the 
foetal  circulation  is  carried  on. 
a,  the  placenta. 

h,  portion  of  the  amnion  which  covers  the  placenta. 

c,  the  chorion. 

d,  the  umbilical  vein. 

e,  branches  of  the  umbilical  vein  going  to  the  liver. 

f,  the  vena  portae. 

g,  hepatic  branches  of  the  preceding. 

h,  the  ductus  venosus. 

i,  the  vena  cava  ascendens  or  inferior. 

Ti,  the  heart  turned  to  the  right. 

l,  the  vena  cava  superior  or  descendens. 

m,  the  ductus  arteriosus. 

n,  the  iliac  arteries,  the  internal  giving  off 

0,  0,  the  two  umbilical  arteries  going  to  the  placenta. 
p,  the  liver  turned  to  the  right  side  in  order  to  show 
the  veins  beneath  it. 


ART.  XVI. 


SEROUS  SYSTEM,  AND  CELLULAR  TISSUE. 


THE  PLEURA  AND  THE  PEKITON.EUM. 

Although,  in  the  description  of  the  contents  of  the 
thorax  and  the  abdomen,  we  have  frequently  had  occasion 
to  advert  to  the  serous  membrane  covering  the  several  or- 
gans, still  the  serous  membranes  in  general,  and  the  pleura 
and  peritonaeum  in  particular,  claim  a more  extended  no- 
tice ; indeed,  the  two  latter  can  be  studied  with  greater 
advantage,  after  an  acquaintance  with  the  anatomy  of  those 
organs  which  they  invest. 

The  serous  system  occupies  the  exterior  of  the  major 
part  of  those  organs,  which  are  lined  by  the  mucous  mem- 
branes : such  as  the  stomach,  the  intestines,  and  the  lungs. 
It  is  found  round  all  those  parts  which  are  essential  to  life, 
as  the  brain,  the  heart,  and  the  abdominal  viscera.  It  also 
lines  the  sides  of  the  cavities  of  the  chest  and  abdomen,  so 
that  the  organs  are  not  in  contact  with  the  sides,  or  with 
the  adjoining  organs,  except  by  the  intermediation  of  the 
peritonfEum. 

The  serous  membranes  present  generally  an  envelope, 
investing  the  organs  so  as  not  to  be  contained  within,  and 
which,  if  it  were  possible  to  dissect  these  organs  from  their 


SEROUS  SYSTEM,  &c. 


305 


spective  surfaces,  would  be  removed  perfectly  entire. 
This  envelope,  in  this  respect,  has  been  compared  to  a 
double  night  cap  placed  on  the  head,  a trifling  simile,  but 
which  however,  conveys  a correct  idea  of  the  manner  in 
which  these  membranes  are  situated.  From  this  disposi- 
tion, it  is  easily  conceived,  that  the  serous  membranes  are 
not  perforated  by  the  vessels  and  nerves  of  their  respective 
organs,  but  that  by  doubling  they  provide  a sheath  for 
those  organs. 

The  internal  surface  of  this  membrane,  although  in  ap- 
position with,  completely  separates  the  adjoining  organs 
over  which  these  membranes  are  spread,  forming,  as  it 
were,  an  integument  to  the  internal  organs,  which  may  be 
compared  to  the  skin  investing  the  e.xterior  of  the  body. 

The  external  surface  of  the  serous  membranes  adheres 
to  the  adjacent  organs  ; these  membranes  are  rarely  found 
unconnected  on  both  surfaces.  The  tunica  arachnoides, 
at  the  base  of  the  brain,  and  a few  others  are  exceptions ; 
and  where  serous  membrane  is  adherent  it  is  perfectly  dis- 
tinct from  the  organ  it  invests : there  is  no  connection  be- 
tween their  reciprocal  organizations;  they  are  merely  united 
by  a loose  cellular  tissue. 

All  the  serous  membranes  are  composed  of  a single 
sheet,  which,  where  it  is  thick,  may  be  separated  into 
cellular  laminjE  ; it  only  differs  from  the  cellular  tissue  in 
being  more  condensed.  By  inflating  the  tissue  beneath, 
the  cellular  structure  is  rendered  very  apparent.  No 
fibres  are  met  with  in  its  structure  (a  distinctive  character 
of  other  organs),  it  is  therefore  similar  to  the  cellular 
tissue. 

The  pleura  is  one  of  the  class  of  serous  membranes,  one 
portion  of  which  forms  the  investing  tunic  of  the  lungs, 
while  the  other  is  attached  to  the  inner  surface  of  the  ribs, 
the  upper  surface  of  the  diaphragm,  the  mediastinum  and 
the  intercostal  muscles.  The  pleura,  covering  the  lungs,  is 

voT,.  II.  39 


30G 


SEROUS  SYSTEftl,  «fcc 


termed  pleura  pulmonalis,  the  reflected  portion,  cos- 

talis,  fhura  iliaphragmatica,  or  pleura  pericardiaca,  in  re- 
ference to  the  surface  to  which  it  adheres. 

The  surface  of  the  heart  is  invested  by  a similar  serous 
membrane,  and  it  is  reflected  so  as  to  form  a sac,  termed 
■pericardium,  which  contains  the  heart. 

The  peritonceum  is  the  most  extensive  of  the  serous 
membranes:  it  is  thin  and  transparent;  it  has  a very 
complicated  course ; not  only  does  it  invest  the  inner 
surface  of  the  parietes  of  the  abdomen,  but  it  forms 
several  remarkable  folds  in  that  cavity,  and  is  prolonged 
under  the  form  of  an  envelope  over  most  of  the  abdominal 
organs. 

It  is  usual  to  describe  the  peritonfEum  as  presenting  a 
sac  without  aperture,  enveloping  those  organs  whose  exter- 
nal appearance  is  smooth  and  glossy,  but,  in  reality,  it  is 
covered  by  fine  villosities.  It  is  everywhere  in  contact 
with  itself.  I have  stated  that  it  is  an  imperforated  sac, 
but,  in  the  female,  there  is  a slight  exception,  for  it  is  found 
to  be  perforated  by  the  fimbriated  extremity  of  the  Fallo- 
pian tube,  the  mucous  membrane  of  which  seems  to  be 
continuous  with  the  peritonosum. 

In  the  umbilical  region,  the  peritonseum  lines  the  pos- 
terior part  of  the  linea  alba,  closes  the  posterior  orifice  of 
the  umbilicus,  and  is  extended  behind  the  wide  muscles 
of  the  abdomen.  On  the  right,  it  meets  the  ascending 
colon ; on  the  left,  the  descending  colon ; and  forms 
around  this  intestine  two  folds,  which  are  named  the 
lumbar  mesocolon,  and  which  serves  to  attach  the  intestine 
to  the  posterior  part  of  the  abdomen.  The  peritonaeum 
passes  before  the  kidneys,  being  separated  from  them  by  a 
greater  or  less  quantity  of  fat  and  cellular  tissue ; then 
covering  the  uterus,  the  spermatic  and  renal  vessels,  the 
vena  cava  and  the  aorta,  it  advances  on  each  side  towards 
the  vertebral  column,  before  which  it  is  reflected  to  form 


SEROUS  SYSTEM,  &c. 


307 


the  mesentery,  or  that  immense  fold  which  supports  and 
envelopes  the  small  intestine. 

In  the  hypogastric  region,  the  peritonseum  descends 
from  the  umbilicus  to  the  pubes,  and,  covering  the  urachus 
and  the  umbilical  arteries,  it  is  directed  over  the  summit 
and  the  posterior  part  of  the  bladder.  It  presents,  how- 
ever, ditferences  according  to  the  se.\  : in  the  male,  it  in- 
vests the  base  of  the  vesiculse  seminales,  and  is  reflected 
over  the  rectum,  constituting  the  mesorectum.  In  the 
female,  the  peritonjEum  is  extended  from  the  bladder  in 
front  of  the  vagina ; it  then  invests  the  anterior  and  poste- 
rior surface  of  the  uterus,  and  is  prolonged,  laterally,  so  as 
to  form  the  broad  ligaments. 

In  the  lateral  parts  of  the  hypogastric  region,  it  is  first 
reflected  upon  the  parietes  of  the  abdomen,  over  the  iliac 
fossa,  covering  part  of  the  iliac  and  psoas  muscles,  embra- 
cing, to  the  left,  the  sigmoid  flexure  of  the  colon,  by  means 
of  the  iliac  mesocolon,  and,  to  the  right,  the  ccecum  and  its 
appendix,  by  means  of  the  mesoccecum.  From  thence  it 
ascends  forwards  behind  Poupart’s  ligament,  and  forms 
two  depressions  on  each  side,  termed  the  inguinal  fossas, 
which  are  separated  from  each  other  by  the  fold  of  mem- 
brane which  supports  the  remains  of  the  umbilical  artery. 
The  external  fossa  is  generally  widest,  and  its  peritonaeum 
dips  a little  into  the  orifice  of  the  inguinal  canal  : posteri- 
orly, the  peritonaeum  is  continued  from  the  iliac  fossa  to  the 
lumbar  mesocolon. 

The  epigastric  portion  of  the  peritonaeum,  to  the  left, 
invests  a considerable  part  of  the  inferior  surface  of  the 
diaphragm,  and  sinks  into  the  most  retired  parts  of  the 
region  of  the  hypochondrium,  as  far  as  the  vertebral  column, 
whence  it  is  reflected  over  the  surface  of  the  spleen,  and 
the  posterior  surface  of  its  vessels.  At  the  cardiac  ex- 
tremity of  the  stomach,  it  is  continued  into  the  anterior 
lamina  of  the  great  omentum.  The  laminiE  of  peritonaeum, 


308 


SEROUS  SYSTEM,  &c. 


which  are  comprised  between  the  spleen  and  the  stomach, 
are  called  the  gastro-sphnic  omenta.  In  the  centre,  the 
peritonjEum  passes  from  the  diaphragm,  upon  the  anterior 
surface  of  the  stomach,  descends  over  the  intestines  tolhe 
most  dependent  part  of  the  abdomen,  and  is  reflected  from 
below  upwards,  as  far  as  the  convex  edge  of  the  colon, 
thus  contributing  to  form  the  great  omentum.  It  then  in- 
vests the  inferior  arch  of  the  colon,  forms  the  inferior  lamina 
of  the  transverse  mesocolon,  and  is  continuous  with  the 
lamina  of  the  mesentery. 

On  the  right,  the  peritona3um  is  reflected  over  the  liver, 
and  forms  foldings  which  constitute  its  ligaments. 

Under  the  neck  of  the  gall  bladder  we  find  a triangular 
aperture,  the  foramen  of  Winslow,  through  which  is  seen 
the  laminae  of  the  peritonaeum,  constituting  the  hypogas- 
tric omentum,  or  the  capsule  of  Glisson;  which  contains 
in  its  duplicature  the  hepatic  and  pyloric  vessels,  the  coro- 
nary vessels  of  the  stomach,  and  the  cystic  and  hepatic 
ducts,  together  with  the  ductus  communis  choledochus. 
This  lamina  is  then  directed  over  the  posterior  surface  of 
the  stomach,  covers  the  upper  surface  of  the  mesocolon, 
and  the  concave  surface  of  the  right  lobe  of  the  liver. 

OMENTA,  OR  EPIPLOA. 

The  omenta  are  composed  of  folds  of  the  peritonaBum 
connected  together  by  cellular  tissue,  containing  fat.  Al- 
though I have  referred  to  them  in  the  preceding  description 
of  the  peritonaeum,  still  it  is  an  advantage  to  the  student 
to  have  before  him  a succinct  and  methodical  arrangement 
of  them. 

The  hepato-gastric  omentum,  or  the  smaller  omentum. 
The  peritonaeum  passes  off  double  from  the  liver  to  the 
lesser  curvature  of  the  stomach.  It  is  limited,  on  the  right. 


SEROUS  SYSTE3I,  &c. 


309 


by  the  large  hepatic  vessels  and  biliary  ducts,  which  are 
inclosed  in  the  capsule  of  Gusson  ; and,  on  the  left,  by 
the  oesophagus  and  the  cardiac  orifice  of  the  stomach.  Be- 
hind the  capsule,  just  named,  we  find  an  aperture  large 
enough  to  admit  a finger,  which  was  first  described  bv 
Winslow,  and  has  been  called  the  foramen  of  Winslow  : 
this  foramen  maintains  a communication  between  the  large 
sac  of  the  omentum,  and  the  common  cavity  of  the  abdo- 
men, The  two  peritonaeal  laminae  of  the  smaller  omentum 
separate  from  each  other  and  invest  the  stomach,  and,  by 
their  continuation,  form  the  anterior  lamina  of — 

The  great  omentum,  a large  fold  of  peritonaeum  : it  is 
free  and  floating  upon  the  front  of  the  convolutions  of  the 
small  intestine.*  It  is  irregularly  quadrilateral  : it  is  at- 
tached, anteriorly,  to  the  great  curvature  of  the  stomach  ; 
and,  posteriorly,  to  the  arch  of  the  colon.  It  is  formed  of 
two  laminae,  each  composed  of  two  lamellae  of  peritonaeum. 
The  anterior  lamina  is  a continuation  of  the  serous  cover- 
ing, from  the  superior  and  inferior  surfaces  of  the  stomach ; 
it  extends,  laterally,  as  far  as  the  commencement  of  the 
duodenum  and  the  inner  surface  of  the  spleen,  to  both  of 
which  it  is  connected.  The  posterior  lamina  has  its  origin 
in  a similar  manner  from  the  serous  membrane  of  the  sur- 
faces of  the  colon.  At  the  opposite  side  of  the  colon^  the 
laminae  unite  to  form  the  mesocolon.  By  the  membrane 
thus  continued,  a large  irregular  sac  is  formed,  of  which 
the  smaller  omentum,  stomach,  and  anterior  portion  of  the 
great  omentum,  constitute  the  anterior,  and  the  posterior 
portion  of  the  great  omentum,  the  colon,  and  mesocolon, 
the  posterior  part  of  the  sac.  In  young  subjects,  the 
parietes  of  the  sac  is  so  complete,  that  it  may  be  inflated 
from  the  foramen  of  Winslow;  but  in  old  and  emaciated 
persons,  the  laminae  of  which  it  is  composed  become  reti- 
cular in  consequence  of  absorption. 


* See  Vol.  I.  Fig.  .197,  i,  i,  i. 


310 


SEROUS  SYSTEM,  &c. 


We  find,  between  the  laminae  of  the  great  omentum,  a 
considerable  quantity  of  fat  and  blood  vessels. 

Tlie  colic  omentum  is  situated  behind  the  great  omentum; 
it  consists  of  a fold  of  the  peritonaeum  which  exists  on  the 
right  side  only,  nearly  filling  the  angle  formed  by  the  union 
of  the  right  and  transverse  portions  of  the  colon.  Fre- 
quently it  extends  as  far  as  the  coecum  or  to  the  spleen. 
Its  two  laminae  are  separated  by  arteries  and  veins  belong- 
ing to  the  colon. 

The  gastro-splenic  omentum  is  formed  in  a similar  man- 
ner by  the  peritonmum,  which,  from  the  fissure  of  the 
spleen,  proceeds  over  the  ckrdiac  extremity  of  the  stomach. 
It  contains  in  its  substance  the  splenic  vessels  and  vasa 
breviora. 

The  omenta,  as  well  as  the  internal  surface  of  other 
serous  membranes,  are  constantly  moistened  with  a fluid 
nearly  resembling  the  serum  of  the  blood.  This  fluid  is 
incessantly  poured  out  by  the  exhalents,  and  constantly 
taken  up  by  the  absorbents.  Its  quantity  varies ; in  the 
natural  state  it  is  merely  a dew,  but  in  dropsies  of  the 
abdomen  it  amounts  to  several  gallons.  Indeed  the  quan- 
tity of  serous  fluid  varies  astonishingly  in  the  different  acute 
and  chronic  diseases  ; and  the  exhalent  surfaces  pour  out 
more  or  less  of  this  fluid,  according  as  they  may  be  prima- 
rily or  sympathetically  affected. 

The  serous  exhalations  give  a facility  to  the  due  actions 
of  the  respective  organs,  by  permitting  them  to  move 
on  each  other  without  injury.  The  great  omentum  is 
supposed  to  preserve  the  intestines  from  the  ill  effects 
which  might  result  from  violent  exertions ; it  serves  to 
retain  their  temperature,  and  to  receive  the  superfluous 
depositions  of  fat. 


SEROUS  SYSTEM,  *!fcc. 


311 


CELLULAR  TISSUE,  ETC. 

The  cellular  tissue  is  distributed  throughout  the  animal 
system ; it  is  composed  of  a very  fine  web,  formed  of  a 
great  number  of  thin  plates,  which  crossing  in  an  endless 
variety  of  directions,  have  between  them  interstices  or 
cells,  which  communicate  together  and  serve  for  the  recep- 
tion of  fat  or  serum.  The  cellular  system,  examined  in 
respect  to  the  organs,  presents,  1st,  an  envelope  or  outward 
limit  to  the  organs  : 2d,  it  enters  freely  into  the  texture  of 
each  organ,  and  constitutes  a part  of  its  structure. 

In  many  parts  the  cellular  tissue  is  very  elastic,  and 
capable  of  extension,  but  in  other  parts  it  is  more  dense 
and  resistant.  In  some  instances  the  cellular  tissue  adheres 
to  one  of  the  surfaces  of  an  organ,  as,  for  instance,  the 
skin  ; in  others  it  entirely  envelopes  it,  as  in  parts  where 
it  is  universally  connected  with  the  adjacent  parts.  The 
skin  universally  exhibits,  wherever  you  examine  it,  a sub- 
jacent cellular  stratum.  This  subcutaneous  cellular  tissue 
varies  considerably  in  its  texture  ; its  density  in  the  scalp 
is  remarkable,  which  on  this  account  is  not  easily  separa- 
ted from  its  aponeurotic  and  muscular  connection.  In 
the  face,  it  is  very  loose,  and  extremely  abundant : it  is 
equally  lax  in  almost  all  parts  of  the  thorax,  and  in  the 
extremities  ; and  therefore,  accomodates  itself  easily  to  the 
motions  of  the  muscles.  It  is  only  in  the  palm  of  the 
hand  and  the  sole  of  the  foot,  that  its  texture,  increasing 
in  density,  forms  a stronger  adhesion  to  the  fascia  and  the 
skin.  This  arrangement  is  highly  favorable  to  the  uses  of 
these  two  parts,  which  must  accommodate  themselves  to 
bodies,  particularly  enabling  the  hand  to  seize,  grasp  and 
hold  them. 

The  texture  of  the  subcutaneous  cellular  tissue  is  dense 
about  the  capsular  ligaments,  for  which  reason  the  adhe- 


312 


SEROUS  SYSTEM,  Ac, 


sion  of  tlie  skin  is  stronger ; hence,  the  contractions  we 
observe  at  those  parts  in  the  extremities  of  infants,  very 
little  fat  being  admitted  into  the  condensed  tissue. 

There  is  a submucous  cellular  tissue,  but  its  texture  is 
more  compressed  than  that  of  the  tissue  we  have  been 
considering  above.  Consequently  there  is  a difficulty  in 
dissecting,  and  separating  it  distinctly  from  its  connections. 

Under  almost  every  part  of  the  serous  system,  and  like- 
wise in  the  two  preceding  situations,  we  find  a cellular 
layer  generally  very  abundant  and  very  loose. 

Around  each  of  the  arteries  there  is  a strong,  dense  and 
elastic  layer,  which  is  sometimes  considered  as  one  of  its 
proper  membranes  : it  arises  almost  imperceptibly  from  the 
adjacent  cellular  tissue,  which  becomes  condensed,  and  is 
so  intimately  united  to  the  vessel,  that  it  may  be  wholly 
detached,  and  forms  a sheath  or  canal  corresponding  to 
that  of  the  artery  it  surrounds  and  supports.  Veins  are 
provided  with  an  external  covering  of  cellular  tissue  analo- 
gous to  that  of  the  arteries. 

With  the  exception  we  have  named,  all  the  organs  are 
completely  surrounded  by  a covering  of  cellular  tissue, 
more  or  less  extensive,  forming  a peculiar  medium  for 
each  ; a medium  in  which  they  are  entirely  immerged,  that 
insulates  them  from  each  other.  After  investing  the  sev- 
eral organs,  the  cellular  tissue  enters  into  their  intimate 
structure,  and  forms  one  of  their  elements.  In  those  organs 
which  are  composed  of  several  parts,  these  parts  are  united 
together  by  it;  thus  in  the  stomach,  intestines,  etc.  the 
different  membranes  of  which  they  are  composed  are  con- 
nected together  by  this  web.  It  sends  a multitude  of  pro- 
cesses into  the  structure  of  the  lungs,  between  the  serous 
membrane  and  their  parenchyma,  between  this  and  the 
bronchi,  and  between  the  bronchi  and  the  mucous  surface. 

In  the  muscles  and  other  organs  the  cellular  tissue  first 
attends  and  surrounds,  through  their  whole  course,  the 


SEROUS  SYSTEM,  &c. 


313 


vascular  and  nervous  ramifications  which  are  found  in  their 
composition;  and  afterwards  unites  the  different  parts 
which  compose  each  organ.  Every  muscular  fasciculus 
or  fibre,  or  vessel,  or  nervous  filament ; every  portion  of 
fascia  or  ligament;  every  glandular  particle,  is  inclosed  in 
a sheath  of  peculiar  cellular  tissue,  which,  in  respect  to 
those  parts,  fulfils  the  same  purpose  as  the  larger  envelope 
does  in  respect  to  the  whole  organ.”* 

Many  fruitless  researches  have  been  made  to  determine 
the  peculiar  organization  of  the  cellular  tissue,  yet  but 
little  is  known,  except  that  on  a minute  inspection  we  find 
an  assemblage  of  innumerable  whitish  filaments  of  extreme 
tenuity,  that  are  spread  over  the  thin  transparent  plates 
that  form  the  cellulae.  Examined  in  a favorable  light,  we 
may  distinguish  its  exquisite  delicacy,  and  when  inflated, 
it  may  be  compared  to  the  air  bubbles  in  a solution  of 
soap.f  There  is  no  doubt,  however,  but  some  of  the  fila- 
ments which  compose  this  tissue  are  exhalent  and  absorb- 
ent vessels  ; and  this  opinion  is  confirmed  when  we  suc- 
ceed in  making  a very  fine  injection  ; we  then  observe  a 
multitude  of  vessels  woven  in  every  direction  with  each 
other,  changing  its  white  and  transparent  hue,  and  con- 
verting it  into  a vascular  net-work. 

Nerves  are  plentifully  distributed  in  the  cellular  tissue, 
but  their  ramifications  are  as  white  as  the  tissue  in  which 
they  abound,  so  that  they  cannot  be  satisfactorily  distin- 
guished from  it. 

The  plates  of  the  cellular  tissue  exhale  a fluid  w^hich  has 
the  greatest  analogy  with  that  of  the  serous  membranes, 
and  which  appears  to  have  the  same  uses  ; namely,  to 
render  the  friction  of  the  plates  easy  on  each  other,  and 
therefore  to  favor  the  reciprocal  motions  of  the  organs,  and 

* Bichat. 

f A beautiful  preparation  may  be  made  of  cellular  tissue,  by  inflating, 
drying,  and  suspending  it  in  rectified  oil  Of  turpentine. 

VOL.  II.  40 


314 


SEROUS  SYSTEM,  &c. 


even  the  relative  change  of  the  different  parts  of  which 
they  are  composed. 


FAT. 

Besides  the  serum,  a fluid  is  found  in  many  parts  of  the 
cellular  tissue  of  a very  different  nature,  which  is  the  fat. 
This  substance  is  contained  in  distinct  cells  that  do  not 
appear  to  communicate  with  the  adjoining  ones.  The  size 
and  form  of  these  cells  are  not  less  variable  than  the  quan- 
tity which  they  contain.  In  some  individuals  scarcely  a 
few  ounces  exist,  while  in  others  there  is  one  or  two  hun- 
dred pounds. 

Human  fat  is  of  a yellow  color  ; inodorous, — becoming 
solid  at  89°  F.  It  is  composed  of  two  proximate  princi- 
ples, recently  discovered  byCnEVREUL,  elaine  and  stearine. 

Some  of  the  offices  of  the  cellular  tissue  maybe  collect- 
ed from  the  preceding  observations : a description  of  this 
part  of  the  animal  fabric  may  very  properly  conclude  a 
work  on  descriptive  anatomy,  since  the  cellular  tissue  con- 
stitutes a bond  of  union,  which,  diffusing  itself  everywhere, 
connects  and  preserves  the  whole  natural  connection  of 
each  part  of  the  organized  structure.  The  subcutaneous 
cellular  tissue  has  many  other  uses  ; from  it  the  skin 
acquires  a freedom  of  motion  over  the  organ  it  covers,  and 
which  is  particularly  observable  in  muscular  actions.  It  is 
also  to  this  tissue,  that  organs  subjacent  to  the  skin  partly 
owe  the  facility  with  which  they  move,  in  those  rapid  or 
powerful  contractions  of  which  they  are  capable. 

As  fat  is  a very  slow  conductor  of  caloric,  it  retains  ani- 
mal heat,  and  consequently  is  useful  in  the  animal  economy 
by  contributing  to  secure  the  subjacent  parts  against  the 
vicissitudes  of  the  atmosphere.  In  the  orbit  it  forms  a sort 
of  elastic  cushion  upon  which  the  eye  moves  with  facility. 


SEROUS  SYSTEM,  &c. 


315 


In  the  palms  of  the  hands  and  the  soles  of  the  feet,  and 
about  the  hips,  it  forms  a layer,  which  renders  pressure 
upon  the  skin  and  other  soft  parts  less  severe.  But  prin- 
cipally this  substance  is  deposited  in  cellular  tissue,  as  a 
store  of  nourishment  intended  to  supply  the  exigencies  of 
the  animal  system ; as  in  instances  where  food  cannot  be 
obtained,  and  in  often  supporting  the  body  under  wasting 
disease,  by  being  absorbed  and  carried  again  into  the  circu- 
lation. 

Together,  the  cellular  tissue  and  fat,  are  useful  as  an 
elastic  vest,  which  guards  the  more  sensitive  parts  of  the 
interior  mechanism.  But  in  contemplating  this  as  well  as 
every  other  part  of  our  organization,  we  cannot  but  admit 
the  admirable  mechanism  exhibited  in  the  human  structure 
and  economy,  and  the  infinite  resources  displayed  by  that 
WISE  and  benevolent  being,  who  planned  the  constitu- 
tion and  preservation  of  our  bodies. 


errata. 

Page  4,  line  6 from  top,  omit  external. 

“ 21,  “ 2 from  bottom,  read  does  for  do. 

“ 29,  “ 6 from  bottom,  read  Acliillis  for  Achilles. 

“ 31,  “ 10  from  top,  read  Tjarietes  for 

264,  “ 4 from  bottom,  read  odorifercc  for  odorijircc. 

“ 303,  “ 6 from  bottom,  read  pulmonary  artery,  for  the  vena  cava  superior  or  de- 

scendens. 


GLOSSARY. 


Abdomen,  (ahdere,  to  hide),  the  lower  venter  or  belly,  containing  or 
hiding  the  intestines,  etc. 

Acantha,  [axavda,  a spine  or  thorn),  sometimes  used  for  the  spine. 

Acetabulum,  (acetuvi,  vinegar),  the  socket  for  the  head  of  the  thigh- 
bone, resembling  an  ancient  vessel  for  holding  vinegar. 

Acini,  (acinus,  a grape  seed),  the  internal  structure  of  several  glands. 

Acoustic,  [uy.ovo,  to  hear),  a term  applied  to  parts  belonging  to  the 
ear,  or  to  sound. 

Acromion,  {uy.gog,  the  extremity,  and  d),«oc,  the  shoulder),  a process 
of  the  scapula. 

Adenology,  [uStjv,  a gland,  and  loyog,  a discourse),  the  doctrine  of 
the  glands. 

Adeps,  fat,  an  oily  matter  contained  in  the  cellular  tissue. 

Adnata,  (adnascor,  to  grow  to),  the  external  coat  of  the  eye. 

Albuginea  Tunica.  The  inner  proper  coat  of  the  testicle  is  thus 
named  from  its  whiteness. 

Albumen,  an  animal  substance  of  the  same  nature  as  the  white  of 
an  egg. 

Alveoli,  (alveus,  a cavity),  the  sockets  for  the  teeth. 

Amnion,  [a/avog,  a lamb),  the  soft  membrane  immediately  surround- 
ing the  foetus. 

Amphiarthrosis,  (cfuqooj,  both,  and  ugdqov,  articulation),  an  articu- 
lation admitting  of  an  obscure  motion. 


318 


GLOSSARY. 


Anastomosis,  {ai'u,  through,  and  awfm,  a mouth),  the  communica- 
tion of  vessels  with  one  another. 

Anatomy,  [ava,  through,  and  ts/hiu),  to  cut),  dissection,  or  that  know- 
ledge of  animal  bodies  acquired  by  dissection. 

Ancon,  the  elbow,  (from  dyjtwi'),  because  the  bones,  being  there 
united,  are  folded  one  into  another.  Hence  also, 

Anconeos,  a muscle  situated  there,  and, 

Anconoid,  a process  of  the  cubit,  from  ctyzwv,  the  elbow,  and 
shape. 

Angeiology,  {ayysiov,  a vessel,  and  f-oyog,  a discourse),  a description 
of  the  vessels. 

Antagonist,  (a^Tf,  against,  and  uyojv,  a struggle),  an  epithet  of  a 
muscle  acting  contrary  to  another. 

Antihelix,  [avTi,  against,  and  siIm,  to  turn  about),  the  external  part 
of  the  ear  opposite  to  the  helix. 

Antithenar,  [avit,  against,  and  devuq,  the  palm  of  the  hand),  one  of 
the  muscles  extending  the  thumb. 

Antitragus,  [avji,  against,  and  rgayog,  a part  of  the  ear),  a promi- 
nence of  the  ear  opposite  to  the  tragus. 

Aorta,  {ao^Ttj ; from  cnjQ,  air,  and  TrjQsm,  to  keep),  the  great  artery  of 
the  heart. 

Aponeurosis,  (uTto,  from,  and  vsvgov,  a nerve),  a tendinous  expan- 
sion, supposed  by  the  ancients  to  be  that  of  a nerve. 

xYpophysis,  (anocpvo),  to  spring  from),  the  process  of  a bone,  and  a 
part  of  the  same  bone.  Epiphysis,  a process  attached  to  a 
bone,  and  not  a part  of  the  same  bone. 

Arachnoides,  {agaxvrj,  a spider’s  web,  and  Bidog,  likeness),  a cobweb- 
like membrane,  the  second  covering  of  the  brain. 

Arteria,  [agg,  air,  and  rggeo),  to  keep),  because  the  ancients  thought 
that  air  was  contained  in  the  arteries. 

Arthrodia,  a joint),  that  kind  of  articulation  which  is  shallow. 

Arytenoides,  [agvTnivu,  an  ewer,  and  eiSog,  shape),  two  cartilages  of 
the  larynx. 

Aspera  Arteria,  faspcr,  rough,  and  arteria,  an  air-vessel),  the 
trachea  or  windpipe. 


GLOSSARY. 


319 


Astragalus,  (otoT^aj'ftio?,  a die),  a bone  of  the  tarsus:  the  coiTes- 
ponding  bones  of  some  animal  were  used  by  the  ancients  as  dice. 

Atlas,  the  first  of  the  cervical  vertebras,  so  named  from  supporting 
the  head,  as  Atlas  was  supposed  to  support  the  world. 

Axilla,  the  arm-pit. 

Aztgos,  (a,  without  and  a J'oke),  a term  applied  to  any  part, 

not  having  a corresponding  part. 


B. 

Basilica,  {^aadevg,  a king),  an  epithet,  by  way  of  eminence,  given 
to  one  of  the  veins  of  the  arm,  to  an  artery  of  the  brain,  and 
to  a process  of  the  occipital  bone. 

Biceps,  (bis,  twice,  and  caput,  a head),  composed  of  two  heads. 

Brachium  {^ga;(vg,  short),  because,  in  general,  from  the  shoulder  to 
the  hand  is  shorter  than  from  the  hip  to  the  foot. 

Bregma,  {^qs/w,  to  moisten),  the  space  between  the  bones  of  the  in- 
fant head  through  which  the  superfluous  humours  of  the  brain 
were  supposed  to  pass. 

Bronchi,  [^goy/og,  the  windpipe),  the  ramifications  of  the  trachea. 

Buccinator,  (huccina,  a trumpet),  a muscle  of  the  cheek,  much  used 
by  trumpeters. 

Bursalogt,  [^vgaa,  a purse,  and  'koyog,  a discourse),  a description  of 
the  bursae  mucosse. 


C. 

C.ECUM,  blind ; a term  applied  in  anatomy  to  an  impervious  canal,  or 
to  a part  which  terminates  abruptly  in  a pouch. 

Calcaneum,  (calx,  the  heel),  the  name  of  the  os  calcis. 

Calvaria,  or  C.alva,  ('caluMS,  bald),  the  upper  part  of  the  cranium, 
which  turns  first  bald. 

Cancelli,  (lattice-work),  the  spongy  substance  in  bones. 

Capillary  Vessels,  (capiUus,  a hair),  the  small  ramifications  of  the 
arteries  and  veins. 


S20 


GLOSSARY. 


Capsule,  a membranous  production  inclosing  a part  like  a bag. 

Caput  Gallinaginis,  (a  wood-cock’s  bead),  a little  eminence  in  the 
urethra  at  the  termination  of  the  ductus  ejaculatorius. 

Cardia,  [xuQdia,  the  heart),  the  superior  opening  of  the  stomach,  so 
called  from  being  situated  near  the  heart. 

Carnivora,  ("caro,  flesh,  and  voro,  to  devour),  animals  that  live  on 
flesh. 

Carotid,  (xuqoo),  to  induce  sleep),  arteries  of  the  head  and  neck, 
which  if  tied,  the  animal  becomes  comatose,  or  has  the  ap- 
pearance of  being  asleep. 

Carpus,  [xuQnog),  the  wrist. 

Cartilage,  gristle,  a matter  softer  than  bone,  but  harder  than  liga- 
ment. 

Caruncula.  This  word  is  a dimunitive  from  caro,  flesh. 

Cellula,  (dimunitive  of  cella,  a cell),  a little  cavity  or  cell. 

Cephalic  Vein,  [xecpah],  the  head),  the  ancients  being  accustomed  to 
open  this  vein  in  disorders  of  the  head. 

Ceratoglossus,  xEQag,  a horn,  and  yloiaaa,  a tongue),  a muscle  run- 
ning from  one  of  the  cornua  of  the  os  hyoides  to  the  tongue. 

Cerebellum,  dim.  of  Cerebrum,  the  brain,  {xuqtj,  the  head). 

Cervix,  the  hinder  part  of  the  neck,  the  fore  part  being  called  Col- 

LUM. 

Choledochus  Ductus  {xolrj,  bile,  and  Sexofim,  to  receive),  the  com- 
mon bile-duct. 

Chorda,  {xogStj,  a cord  or  assemblage  of  fibi'es),  a term  applied  to  a 
nerve  of  the  tympanum,  to  the  spermatic  vessels,  etc. 

Chorion,  domicilium),  the  outer  membrane  involving  the 

foetus;  or  chorus,  this  membrane  being  supplied  with 

many  blood  vessels  in  the  quadruped. 

Choroides,  so  called  on  account  of  its  many  blood  vessels,  resemb- 
ling the  chorion. 

Chyle,  {xvlog,  the  juice),  the  milk-like  fluid  in  the  lacteal  vessels. 

Crystalline,  [xQvaiaU-og),  a term  applied  to  the  lens,  from  its  re- 
semblance to  ice. 

Clavicula,  (dim.  of  clavis,  a key),  the  clavicle  or  collar-bone ; so 
called  from  its  resemblance  to  an  ancient  key. 


GLOSSARY 


321 


Ci,TNOiD,  [y.livTj,  a bed,  and  siSog,  shape),  processes  of  the  sella  turci- 
ca of  the  sphenoid  bone,  so  called  from  their  resemblance  to  a 
couch. 

Clitoris,  [TtleiM,  to  conceal),  a part  of  the  female  pudendum  con- 
cealed by  the  labia  majora. 

Coccyx,  [xor.xv^,  a cuckoo),  the  lower  end  of  the  spine,  so  called  from 
its  resemblance  to  the  beak  of  that  bird. 

Cochlea,  (xo^Xog,  a conch),  a cavity  of  the  ear  resembling  the  shell 
of  a snail. 

CfflcuM,  the  blind  intestine. 

CffiLiACA,  (xodioc,  the  belly),  the  name  of  an  artery  in  the  abdomen. 

Colon,  {y.wlop),  the  first  portion  of  the  large  intestine. 

CoMMissuRA,  (conimitto,  to  join  together),  applied  to  parts  which  unite 
the  hemispheres  of  the  brain. 

Concha,  {y-oy/rj,  a shell)  applied  to  the  hollow  of  the  ear  from  its  re- 
semblance to  a shell. 

Condyle,  {xovdvlog,  a joint,  a knuckle,  a knot),  an  eminence  in 
several  of  the  joints. 

Conglobate,  (conglobatus,  gathered  together  in  a circle),  a gland  sub- 
sisting by  itself,  like  those  of  the  absorbent  system. 

Conglomerate,  (conglomeratus,  heaped  together),  a gland  composed 
of  various  glands. 

CoRACo ; names  compounded  with  this  word  belong  to  muscles 
which  are  attached  to  the  coracoid  process  of  the  scapula. 

Coracoid,  [voga^,  a crow,  and  sidog,  resemblance),  like  the  beak  of  a 
crow. 

Cornu,  (a  horn),  applied  to  a process  resembling  a horn. 

Coronary,  (corona,  a crown),  vessels  so  called  from  surrounding  the 
parts  like  a crown. 

CoRONOiD,  (xogavj],  a crown,  and  et^oc,  shape),  a process  shaped  like 
a crown. 

Corpus  Callosum,  (corpus,  a body,  and  callus,  hard),  part  of  the 
medullary  substance  of  the  brain,  supposed  to  be  firmer  than 
the  rest. 


VOL.  II. 


41 


322 


GLOSSARY. 


CoRTicALis  Substantia,  (cortex,  bark),  tlie  exterior  or  cortical  sub- 
stance of  the  brain. 

Costa;,  ( custodio,  to  guard),  the  ribs,  because  they  guard  the  heart,  etc. 

Cotyledons,  [xoxvh-j,  a cavity),  glands,  in  some  animals,  dispersed 
over  the  chorion. 

Cotyloid,  (jforuA;;,  an  old  measure,  and  shape),  the  cavity  for 

receiving  the  head  of  the  thigh-bone,  resembling  the  rotuli. 

CoxiE,  the  haunches. 

Cranium,  [xquviov,  the  skull,  quasi,  y.aqaviov,  from  xuqa),  the  head. 

Cremaster,  {x()Efiab),Xo  suspend),  a muscle  so  called,  because  it  sus- 
pends the  testicle. 

Cribriform,  (crihrum,  a sieve),  perforated  like  a sieve. 

Cricoid,  {xQiy.og,  a ring,  and  ei,dog,  shape),  the  annular  cartilage  of 
the  larynx. 

Crista  Galli,  a portion  of  the  ethmoid  bone,  so  called  from  its  re- 
semblance to  a cock’s  comb.  Crista,  a term  applied  to  other 
parts  which  resemble  a crest. 

Crura,  (a-ns,  a leg),  applied  to  some  parts,  from  their  resemblance  or 
analogy  to  a leg. 

Crypts,  (xgvnra),  to  hide),  mucous  follicles  which  are  concealed. 

Cubitus,  (a  cubando),  that  part  of  the  arm  from  the  elbow  to  the 
wrist ; because  the  ancients,  during  meals,  used  to  recline 
upon  it. 

CuBoiDEs,  (xv^og,  a cube,  and  eidog,  shape),  a bone  of  the  foot,  re- 
sembling a cube. 

CucuLLARis,  (cucullus,  a cowl  or  hood),  a broad  muscle  of  the  scap- 
ula, so  called  from  its  shape. 

Cuneiform,  (cuneus,  a’ wedge),  wedge-shaped. 

CuTicuLA,  (the  dim.  of  cutis,  the  skin),  the  scarf-skin. 

Cutis,  the  skin. 

Cysticus  Ductus  [xvang,  a bladder,  ductus,  a duct),  the  duct  leading 
from  the  gall-bladder. 


GLOSSARY. 


323 


D. 

Dartos  {SsQca,  to  excoriate),  muscular  fibres  which  contract  the  scro- 
tum. 

Decidua,  (decido,  to  fall  off),  a membrane  thrown  off’ from  the  uterus 
after  parturition. 

Deltoid,  [Jehu,  the  fourth  letter  of  the  Greek  alphabet,  and  sidog, 
shape),  resembling  the  Greek  letter 

Dermis,  [dsQfxa),  the  more  solid  skin. 

Detrusor  Urin.^:,  (detrudere),  to  thrust  or  squeeze  out  of. 

Diaphragm,  {SiccfpQaaaco,  a partition),  the  transverse  muscle  which 
separates  the  thorax  from  the  abdomen. 

Diastole,  (diaatsllco,  to  relax),  the  dilatation  of  the  heart,  auricles, 
and  arteries,  opposed  to  systole,  the  contraction  of  the  same 
parts. 

Diarthrosis,  [diugOgoco,  to  articulate),  a movable  connection  of 
bones. 

Digastric,  {Sig,  twice,  and  -/aaTrjg,  a belly),  having  two  bellies. 

Diploe,  [dinloog,  double),  the  spongy  substance  between  the  two 
tables  of  the  skull. 

Duodenum,  (duodenus,  consisting  of  twelve,  viz.  fingers’  breadth),  the 
first  portion  of  the  small  intestine,  so  called  from  its  general 
length. 

Dura  Mater,  (durus,  hard,  and  mater,  a mother),  the  outermost 
membrane  of  the  brain  ; the  ancients  finding  it  harder  than, 
and  supposing  it  to  give  origin  to,  the  other  membranes  of  the 
body. 


E. 

Elaine,  [elaiov,  oil),  the  more  ffuid  part  of  one  of  the  proximate 
principles  of  fat. 

Embryo,  [ev,  in,  and  §qvu>,  to  germinate),  the  ovum  in  utero  before 
the  fourth  month,  after  which  it  is  called  foetus. 


324 


GLOSSARY. 


Emulgents,  (emulgeo,  to  milk  out),  the  arteries,  and  veins  of  the 
kidneys,  so  called  because,  according  to  the  ancients,  they 
strained,  and,  as  it  were,  milked  the  serum  through  the  kid- 
neys. 

Emunctores,  (emungo,  to  wipe  away),  glands  which,  according  to 
the  ancients,  received  the  excrementitious  matter  from  the 
noble  parts  ; as  the  parotids  from  the  brain,  the  axillary  glands 
from  the  heart,  and  inguinal  glands  from  the  liver. 

Exarthrosis,  (er,  in,  and  aqdqov,  a joint),  an  articulation  of  bones, 
the  same  as  arthrosis. 

Encephalon,  [ev,  in,  and  xecpuhj,  the  head),  the  brain. 

Enteric,  [evtbqov,  an  intestine),  belonging  to  the  intestines. 

Epicranidm,  [em,  and  xgaviov),  the  integuments  and  aponeurotic 
expansion  which  are  extended  over  the  cranium. 

Epidermis,  {stu,  upon,  and  deg/za,  the  skin),  the  cuticle. 

Epididymis,  {em,  upon,  and  didv/nog,  twins,  the  testicles),  the  small 
oblong  body  which  lies  above  the  testicle. 

Epigastric,  (etw,  upon,  and  yaaTtjQ,  the  stomach),  the  superior  part 
of  the  abdomen. 

Epiglottis,  {em.,  ujion,  and  yhojxug,  lingula),  one  of  the  five  cartila- 
ges of  the  larynx,  situated  above  the  glottis. 

Ephippiem,  {stu,  upon,  and  irtnog,  a horse),  part  of  the  os  sphenoides, 
so  called  from  its  resemblance  to  a saddle. 

Epiphysis,  {em,  upon,  and  gpuw,  to  grow),  see  Apophysis. 

Epiploon,  (sm,  ujron,  and  nleot,  to  sail),  the  omentum,  or  that  serous 
membrane  of  the  abdomen  which  covers  the  intestines,  and 
hangs  from  the  bottom  of  the  stomach. 

Ethmoid,  MO?,  a sieve),  so  called  because  it  is  perforated  like  a sieve. 

F. 

Falciform,  (falx,  a scythe),  shajied  like  a scythe. 

Fascia,  (fascia,  a band),  a membranous  expansion  of  certain  muscles 
like  a sheath. 

Fasciculus,  a little  bundle,  diminutive  of  fascis,  a bundle. 


GLOSSARY. 


325 


Fauces,  (the  plural  of  faux),  the  top  of  the  throat. 

Fibrin,  a peculiar  organic  compound,  which  is  the  most  abundant 
constituent  of  the  soft  solids  of  animals. 

Fibula,  (a  clasp),  the  lesser  bone  of  the  leg,  which  is  thus  named 
from  being  placed  opposite  to  the  part  where  the  knee-buckle 
or  clasp  was  formerly  used. 

Fiimbria,  a fringe,  a term  applied  to  parts  of  a fringe-like  appearance. 

Fffixus,the  child  in  the  womb  past  the  fourth  month,  and  fully  formed. 

Follicle,  (follis,  a bag),  very  minute  secreting  cavities. 

FR.ENUM,  (a  bridle),  the  membranous  ligament  under  the  tongue,  and 
the  one  tying  the  prepuce  to  the  glans. 

G. 

Galactophorous,  (yo^.a,  milk,  and  cpsqm,  to  carry),  conveying  the 
milk. 

Ganglion,  (yayyliop),  an  enlargement  in  the  course  of  a nerve. 

Gastric,  (yaan/q,  the  stomach),  appertaining  to  the  stomach. 

Gastrocnemius,  {yaaTijq,  the  belly,  and  xvrj/ixrj,  the  leg),  the  muscle 
forming  the  thick  of  the  leg. 

Gastro-Epiploic,  [yacmjq,  the  stomach,  and  eranloov,  the  caul),  be- 
longing to  the  stomach  and  omentum. 

Gelatine,  (gelu),  jelly. 

Genio,  [yevEiov,  the  chin) ; names  compounded  with  this  word  be- 
long to  muscles  attached  to  the  chin. 

Gestation,  (gestaiio  uterina),  the  period  of  pregnancy. 

Ginglymus  (yryyZa^uoc,  a hinge),  articulation  admitting  flexion  and  ex- 
tension. 

Glandula,  (dim.  of  glans),  a nut  or  acorn. 

Glenoib,  [y^qv-r],  a cavity),  a part  having  a shallow  cavity. 

Gliadine,  [ylitt,  glue),  one  of  the  constituents  of  gluten. 

Glomer,  a convoluted  bundle  of  glands. 

Glosso,  (j'AwffffO!,  the  tongue) ; names  compounded  with  this  word 
are  applied  to  muscles  attached  to  the  tongue. 


326 


GLOSSARY. 


Glottis,  [yltairig,  lingida),  the  superior  opening  of  the  larynx. 

Gluteus,  [ylovTog,  the  buttock),  muscles  forming  part  of  the  buttocks. 

Gomphosis,  {yoficpoM,  to  drive  in  a nail),  an  articulation  of  bones,  like 
a nail  in  a piece  of  wood. 

H. 

Hjemorrhoidal,  {aifia,  blood,  and  qeo),  to  flow),  a term  applied  to  the 
vessels  of  the  rectum,  because  they  often  bleed. 

Harmo.ma,  (uQuoi’ia,  a close  joining),  a species  of  immovable  artic- 
ulation. 

Helix,  {sdoj,  to  turn  about),  the  outer  bar  or  margin  of  the  external 
ear. 

Hepatic,  {rjnaQ,  the  liver),  applied  to  parts  belonging  to  the  liver. 

Hyaloid,  [vulog,  glass),  the  capsule  of  the  vitreous  humour  of  the 
eye. 

Hymex,  (the  god  of  marriage),  the  membrane  situated  at  the  entrance 
of  the  virgin  vagina. 

Hyo  ; names  compounded  with  this  word  belong  to  muscles  which 
are  attached  to  the  — 

Hyoides,  Os,  (d,  and  eidog,  shape),  a bone  of  the  tongue  resembling 
the  Greek  upsilon,  v. 

Hypochoxdrium,  [ino,  under,  and  ‘/ovdqog,  a cartilage),  the  upper 
region  of  the  abdomen,  under  the  cartilages  of  the  ribs. 

Hypogastric,  {ino,  under,  and  yao'n/^,the  belly),  the  lower  region  of 
the  fore  part  of  the  abdomen. 

Hypoglossus,  (i5tto,  under,  and  ylfuaau,  the  tongue),  parts  which  lie 
under  the  tongue. 

Hypothenar,  [vno,  under,  and  devag,  the  palm  of  the  hand),  one  of 
the  muscles  contracting  the  thumb. 


\. 

Ileum,  [eileo,  to  turn),  a portion  of  the  small  intestine,  so  called 
from  being  found  convoluted. 


GLOSSARY. 


327 


Incisores,  (incidere,  to  cut),  the  fore-teeth. 

Incus,  (an  anvil),  a small  bone  of  the  internal  ear,  with  which  the 
malleus  is  articulated. 

Index,  (indico,  to  point  out),  the  fore  finger. 

Infundibulum,  (a  funnel),  a tube  leading  from  the  brain  to  the  pitui- 
tary gland. 

Innominatum,  parts  which  have  no  proper  name. 

Interfemineum  ; vide  Perin.eum. 

Interosseous,  (inter  and  os),  a term  applied  to  parts  situated  between 
bones. 

Iris,  (the  rainbow),  the  membrane  round  the  pupil  of  the  eye,  deriv- 
ing its  name  from  its  various  colors. 

Ischium,  (to/w,  to  support),  that  part  of  the  os  innominatum  upon 
which  we  sit. 


J. 

Jejunum,  (empty),  a portion  of  the  small  intestine,  so  called  from 
being  generally  found  empty. 

JuGALE,  Os,  the  zygoma. 


L. 

Lacunje,  (little  cavities),  the  excretory  ducts  of  the  urethra,  vagina, 
etc. 

Lambdoidal,  resembling  the  Greek  lambda,  A. 

Lamella,  dim.  of — 

Lamina,  a scale  or  plate.  It  is  used  for  the  foliated  structure  of  bones 
or  other  organs. 

Larynx,  (^of^vj'l),  the  superior  part  of  the  trachea. 

Linea  Alba,  a white  line  formed  by  the  meeting  of  the  tendons  of 
the  abdominal  muscles. 

Lumbricales,  (hmbricus,  an  earth-worm),  four  muscles  of  the  hand 
and  foot. 


GLOSSARY. 


QC)Q 

OZO 


M. 


M.iSSETER,  (liiuaacicouai,  to  chew),  a muscle  which  assists  in  chewing. 

Mastoid,  [finaTog,  a breast),  shaped  like  a nipple  or  breast. 

JVIaxidla,  the  jaw. 

BIeco.mdm,  a poppy),  the  excrements  of  the  fmtus  are  thus 

called,  because  they  have  some  resemblance  to  opium  in 
color. 

Mediana  Vena,  the  middle  vein  of  the  arm,  between  the  basilic  and 
cepludic. 

Mediastinum,  (medium,  the  middle),  a middle  portion  separating 
parts  from  each  other. 

Medulla  Spinalis,  the  spinal  marrow  or  cord. 

Membrana  Nictitans,  (nicio,  to  wink),  a membrane  with  which 
birds  can  occasionally  cover  the  eye. 

Meninges,  (firjmyg,  a membrane,)  membranes  which  inclose  the  brain. 

Mesentery,  [fieaoc,  the  middle,  and  svtsqov,  the  intestine),  the  mem- 
brane in  the  middle  of  the  intestines,  by  which  they  are  at- 
tached to  the  spine. 

Meseraic,  [fisaoc,  the  middle,  and  uquiu,  the  small  intestine,)  the 
same  as  the  last  article. 

Mesocolon,  (ueaog,  the  middle,  xcoIop,  the  colon),  that  part  of  the 
mesentery  in  the  middle  of  the  colon. 

IMetacarpus,  [f-iera,  after,  and  xuQnog,  the  wrist),  that  piart  of  the 
hand  between  the  carpus  and  fingers. 

Metatarsus,  {imstu,  after,  and  raQuog,  the  tarsus),  that  part  of  the 
foot  between  the  tarsus  and  toes. 

Mitralis  Valvula,  (mitra,  a mitre),  valves  at  the  left  ventricle  of  the 
heart,  like  a mitre. 

Molar  Teeth,  the  double,  or  grinding  teeth. 

Mucus,  the  mucus  of  the  nostrils),  a transparent,  saline,  gluti- 

nous fluid. 

Mylo,  [jjivlrj,  a grinder  tooth) ; names  compounded  of  this  word  be- 
long to  muscles  that  are  attached  near  the  grinders. 


GLOSSARY. 


329 


Myoides  Pla.tysma,  a muscular  expansion  on  the  neck.  See  Pla- 
TYSMA. 

Myology,  (/nvg  and  Aoj'og),  the  doctrine  of  the  muscles. 

N. 

Naviculare,  (navicula,  a small  boat),  a bone  of  the  carpus,  and  also 
of  the  tarsus. 

Neurilemma,  {vevqov,  a nerve,  and  Isfiiiu,  a coat),  the  sheath  of  a 
nerve. 

Neurology,  [vevqov,  a nerve),  the  doctrine  of  the  nerves. 

Nymph.e,  two  semicircular  glandular  membranes  in  the  pudendum 
mulibre,  so  called  because  they  direct  the  course  of  the  urine. 

O. 

Odontoides,  (otioi/?,  a tooth,  and  eidog,  shape),  tooth-like. 

CEsophagus,  (otw,  to  carry,  epayw,  to  eat),  the  canal  leading  from  the 
pharynx  to  the  stomach,  carrying  what  is  swallowed  into  the 
stomach. 

Olecranon,  [wlevr],  the  cubit,  xqavov,  the  head),  the  elbow,  or  head 
of  the  ulna. 

Omentum,  fomen,  a guess),  the  caul,  so  called  because  the  ancient 
priests  prophesied  from  an  inspection  of  this  viscus. 

Omo,  [apog,  the  shoulder) ; names  compounded  of  this  word  belong 
to  muscles  which  are  attached  to  the  scapula. 

Omo-Plata,  [ojpog,  the  shoulder,  and  nlazvg,  broad),  the  scapula  or 
shoulder-blade. 

Ophthalmic,  [ocpdalpog,  an  eye),  relating  to  the  eye. 

Organ,  [ogyavov),  a part  which  has  a determined  office  in  the  animal 
economy. 

OsMAZOME,  (oaprj,  flavor,  and  tfopog,  broth),  a peculiar  principle  ob- 
tained from  muscular  fibre,  having  the  taste  and  smell  of  broth. 

Osteology,  (ootbov,  bone,  and  'koyog,  a discourse),  the  doctrine  of  the 
bones. 


VOL.  II. 


42 


330 


GLOSSARY. 


P. 

Pai.pi,  (palpo,  to  grope  or  feel  one’s  way),  feelers. 

Pampixiformis,  (pampinus,  a vine-tendril,  and  forma,  shape).  The 
spermatic  vessels  form  a plexus,  which,  from  its  similitude  to 
the  tendrils  of  a vine  is  called  pampiuiformis. 

Pancreas,  {itav,  all,  and  y.QBug,  flesh),  a gland  of  the  abdomen. 

Panniculus  Carnosus,  (pannus,  a covering,  and  caro,  flesh,)  a fleshy 
covering. 

Parenchyma,  (Tr«5£7;vew,  to  pour  through),  a substance  connecting 
the  vessels,  etc.  of  the  lungs,  liver,  etc. 

Parietaeia,  (paries,  a wall),  hones  of  the  cranium,  serving  as  a wall 
to  the  brain. 

Parotid,  [naga,  near,  and  onog,  the  gen.  of  ovg,  the  ear),  a gland  sit- 
uated near  the  ear. 

Patella,  (dim.  of  patina,  a pan),  the  knee-pan. 

Pat HETiciE,  (jraSoj,  passion),  the  fourth  pair  of  nerves,  because  by 
means  of  these,  the  eyes  express  certain  passions. 

Pelvis,  [nelv^,  a basin),  the  basin  of  the  kidneys,  or  the  lower  part  of 
the  abdomen,  in  which  the  bladder  and  rectum  (and  in  women 
also  the  uterus)  are  contained. 

Pericardium,  [nsgi,  around,  and  xugdia,  the  heart),  the  membrane 
surrounding  the  heart. 

Perichondrium,  (jie^i  and  xov8gog),  synovial  membrane  covering 
cartilage. 

Pericranium,  [negi,,  around,  and  xgaviov,  the  cranium),  the  mem- 
brane covering  the  bones  of  the  cranium. 

PERIN.EUM,  [rtEgivaiov,  to  flow  round,  because  that  part  is  generally 
moist),  the  space  between  the  external  parts  of  generation  and 
the  anus. 

Periosteum,  [negi,,  around,  and  oaxsor,  a bone),  the  membrane  sur- 
rounding the  bones. 

Peristaltic,  (nsgiaielXu),  to  contract),  the  motion  of  the  intestines. 

PERITON.EUM,  (Tre^trerw,  to  extend  round),  the  membrane  lining  the 
abdomen,  and  covering  its  organs. 


GLOSSARY, 


331 


Perone,  [nsqovTj),  the  fibula  or  small  bone  of  the  leg. 

Petrosum,  Os,  (Tter^a,  a rock),  part  of  the  temporal  bone. 

Phalanx,  (an  army),  the  bones  of  the  fingers  and  toes  are  called 
phalanges,  from  their  regularity. 

Pharynx,  [(paQvy^),  a membranous  bag  at  the  back  end  of  the  mouth, 
leading  to  the  stomach. 

Phrenic,  (q)§svsg,  the  diaphragm,  the  mind,  because  the  dia- 
phragm was  supposed  to  be  the  seat  of  the  mind),  the  name  of 
a nerve,  etc. 

Physiology,  {cpvaig,  nature),  that  science  which  has  for  its  object  a 
knowledge  of  the  actions  and  functions  of  the  living  body. 

PiA  Mater,  the  innermost  membrane  around  the  brain. 

Picromel,  (niy.Qog,  bitter,  and  fieh,  honey),  the  characteristic  princi- 
ple of  bile. 

Pisiform,  (pea-like),  a term  applied  to  the  fourth  bone  of  the  first 
row  of  the  carpus. 

Pituitary,  (producing  phlegm),  a term  applied  to  the  membrane  of 
the  nose,  etc. 

Placenta,  [nloc^,  a cake),  the  after-birth. 

Plantaris,  (planta,  the  sole),  parts  situated  in  the  sole. 

Platysma-Myoides,  {nlaTvg,  broad,  pvg,  a muscle,  and  eidog,  shape), 
a muscle  of  the  neck. 

Pleura,  {Tzi-Evgcc,  the  side),  a serous  membrane  lining  the  cavity  of 
the  thorax. 

Plexus,  (photo,  to  weave  together),  a kind  of  net-work  of  blood  ves- 
sels or  nerves. 

Pneumonic,  [nvBvfmi',  the  lung),  appertaining  to  the  lungs. 

Popliteus,  (poples,  the  ham),  a muscle  of  the  leg. 

Prepuce,  the  fore-skin  of  the  penis,  which  the  eastern  nations  gen- 
erally cut  off. 

Processus,  (procedo,  to  start  out),  an  eminence  of  bone. 

Prostate,  {^§o,  before,  and  larruu,  to  stand),  a gland  situated  before 
the  vesicula  seminales. 

Psoas,  {ipoai,  the  loins),  a muscle  so  named  from  its  situation. 

Pterygoid,  (mega,  a wing),  a process  resembling  a wing. 


332 


GLOSSARY. 


Ptertgo-Staphylini,  a wing,  and  arucpvh],a  grape),  mus- 

cles arising  from  the  pterygoid  process  of  the  os  sphenoides, 
and  inserted  into  the  uvula. 

Pudenda,  (pudor,  shame),  the  parts  of  generation- 
Pdpilla,  ( a little  puppet),  the  round  aperture  in  the  iris  of  the  eye. 
Pylorus,  (nvXa)Qog,  the  keeper  of  a gate),  the  lower  orifice  of  the 
stomach,  guarding  the  entrance  of  the  bowels. 

Pyramidalis,  a muscle  having  the  form  of  a pyramid. 

Pyriform,  (pyrus),  a muscle  having  the  form  of  a pear. 

R. 

Rachidian,  [Qu^ig,  the  spine),  appertaining  to  the  spine. 

Radius,  (the  spoke  of  a wheel),  the  small  bone  of  the  fore-arm. 
Ranular,  like  a frog  or  toad. 

Raphe,  {qamb),  to  sew),  a line  having  the  appearance  of  a seam. 
Rectum,  the  straight  gut,  the  last  of  the  intestines. 

Region,  a term  applied  to  the  respective  divisions  of  the  body. 
Renal,  appertaining  to  the  kidney,  from  — 

Renes,  the  kidneys,  through  which  the  urine  flows. 

Retina,  (rete,  a net),  the  net-like  expansion  of  the  optic  nerve  on  the 
inner  surface  of  the  eye. 

Rhomboides,  a muscle  so  called  from  resembling  a geometrical  figure 
[qofi^og),  the  sides  of  which  are  equal,  but  not  right  angled. 
Rotula,  (dim.  of  rota,  a wheel),  the  knee-pan. 

S. 

Sacrum,  (sacred),  a bone  so  called  because  it  was  offered  in  sacrifice. 
Sagittalis,  (sagitta,  an  arrow),  a suture  in  the  cranium. 

Saliva,  the  fluid  secreted  in  the  mouth. 

Salvatella,  (salvo,  to  preserve),  a vein  of  the  foot,  the  opening  of 
which  was  said  to  preserve  health  and  cure  melancholy. 
Sanguis,  the  blood. 

Saphena,  [anepyg,  manifest),  the  most  obvious  vein  of  the  leg. 


GLOSSARY. 


333 


Sartorius,  (sarior,  a tailor),  the  muscle  by  means  of  which  the  tai- 
lor lays  his  legs  across. 

ScALENi,  [cr^alrjvog,  a geometrical  figure  with  three  unequal  sides), 
muscles  of  the  neck. 

ScAPHA,  {(jxacprj,  a little  boat),  the  depression  of  the  outer  ear  before 
the  anti-helix. 

ScAPHoiDES,  (resembling  a boat),  a bone  of  the  carpus,  and  also  of 
the  tarsus. 

Scapula,  the  shoulder-blade. 

Sclerotic,  (aTtlrjQog,  hard),  the  outermost  or  hardest  membrane  of 
the  eye. 

ScuTiFORM,  shaped  like  a shield. 

Sebaceous,  suety  ; a term  applied  to  glands  which  secrete  an  unctuous 
matter. 

Sella  Turcica,  Sella  Equina,  Sella  Sphenoides,  are  various 
names  for  a part  of  the  sphenoid  bone  resembling  a Turkish 
saddle. 

Septum  Cordis,  (sepes,  a hedge),  the  fleshy  substance  which  sepa- 
rates the  right  from  the  left  ventricle  of  the  heart. 

Sesamoid,  [aTjauf^r],  an  Indian  bean),  small  bones  in  the  hands  and 
feet  resembling  the  semen  sesami. 

Sigmoid,  resembling  the  Greek  ?,  sigma. 

Skeleton,  [axelXa,  to  dry),  the  articulated  dry  bones  of  an  animal. 

SoLEus,  (solea,  sole),  a muscle  of  the  leg  having  the  form  of  that  fish. 

Spermatic,  {(msQpa,  seed),  parts  belonging  to  the  testis  or  ovarium. 

Sphenoid,  [acprjv,  a wedge),  shaped  like  a wedge. 

Sphincter,  [ucpiyya,  to  constrict),  the  name  of  several  muscles,  the 
office  of  which  is  to  close  the  apertures  around  which  they 
are  placed. 

Splanchnology,  [cmluYXfov,  the  viscera),  the  description  of  the  in- 
ternal organs. 

Splenius,  ['jnlrjy,  the  spleen),  a muscle  so  named  from  its  resemblance 
to  that  organ. 

Squamous,  (squama,  a scale),  covering  as  the  scales  of  fishes  do  each 
other. 


33^ 


GLOSSARY. 


Stapes,  (a  stirrup),  one  of  the  small  bones  of  the  internal  ear. 

Stearine,  [areaQ,  fat),  the  more  solid  part  of  one  of  the  proximate 
principles  of  fat. 

Stomachus,  [uTOfitt,  a mouth,  and  ;(sco,  to  pour),  the  stomach. 

Styloid,  (stylus,  a pencil),  a process  likeajjencil  on  the  temporal  and 
other  bones.  , 

SuccENTURiATUS,  ( succenturiarc) , to  supply  the  place  of  another. 

Suture,  ('sMfwa,  a seam),  an  appearance  which  is  most  obvious  in 
in  that  union  of  the  bones  of  the  skull  constituting  the  dove 
tail  suture. 

Symphysis,  [avftcpvo),  to  grow  together),  the  connection  of  bones 
which  have  no  manifest  motion. 

Synarthrosis,  {auv,  with,  and  kqOqov,  a joint),  articulation  without 
manifest  motion. 

Synchondrosis,  [aw,  with,  and  xovSqog,  a cartilage),  articulation  by 
means  of  intervening  cartilage. 

Syndesmology,  [awSeayog,  a ligament),  the  doctrine  of  ligaments. 

Syndesmosis,  the  connection  of  bones  by  ligaments. 

Syneurosis,  [aw,  with,  and  vbvqov,  a nerve),  the  connection  of  bones 
by  tendon,  formerly  mistaken  for  nerve. 

Synthesis,  to  put  together),  the  anatomical  connection  of 

the  bones  of  the  skeleton. 

Syssarcosis,  [aw,  with,  and  auq^,  flesh),  the  connection  of  bones  by 
muscle. 

Systole,  [awTsllw,  to  contract);  vide  Diastole. 

T. 

Talus,  (a  die),  a bone  of  the  tarsus.  V 

Tarsus,  the  space  between  the  bones  of  the  leg  and  the  metatarsus. 

Temporal  ; bones,  etc.  have  been  so  named  on  account  of  occupying 
the  region  of  the  head  on  which  the  hair  generally  first  begins 
to  turn  gray,  thus  indicating  the  age. 

Tendon,  [xeivb),  to  extend ),  a fibrous  cord  at  the  extremity  of  a muscle. 

Tentacula,  (Unto,  to  seize),  organs  by  which  certain  animals  attach 
themselves  to  surrounding  objects. 


GLOSSARY. 


335 


Teres,  (round),  the  name  of  a muscle. 

Testis,  (a  witness,  quia  est  quasi  testis  virilitatis),  the  testicle. 

Thalamus,  {dalufiog,  a bed),  applied  to  a part  of  the  brain  from 
which  the  optic  nerve  takes  its  origin. 

Theca,  (a  sheath);  the  spinal  canal  is  often  called  theca  vertebralis. 

Thenar,  (the  palm  of  the  hand),  a muscle  extending  the  thumb. 

Thorax,  [doqag,  the  chest),  or  that  part  of  the  body  which  contains 
the  heart  and  lungs. 

Thymus,  {dv/iog,  a bulbous  root),  a temporary  gland  in  the  thorax. 

Thyreo  ; names  compounded  with  this  word  belong  to  muscles 
which  are  attached  to  the  — 

Thyroid,  {dugsog,  a shield),  a cartilage  of  the  larynx  compared  to  a 
shield. 

Tibia,  (a  pipe  or  flute),  the  great  bone  of  the  leg. 

Tonsils,  the  round  glands  placed  between  the  arches  of  the  palate. 

Trachea,  (r^cKj/ug,  rough),  the  windpipe. 

Tragus,  (a  goat),  a small  eminence  of  the  external  ear,  upon  which 
hair  often  grows  like  the  beard  of  a goat. 

Trapezoid,  like  a trapezium. 

Trochanter,  [rgo^ao),  to  run  or  to  roll),  a process  of  the  thigh  bone, 
the  muscles  inserted  into  which  greatly  contribute  to  the  ac- 
tion of  running. 

Trochlea,  {Tgo%aha,  a pulley),  a kind  of  cartilaginous  pulley. 

Trochlearis,  an  articulation  where  one  part  moves  round  another 
like  a pulley. 

Tub®  Fallopian.®,  two  canals  at  the  fundus  uteri  of  a trumpet  fonn, 
described  by  Fallopius. 

Tympanum,  the  drum  of  the  ear. 


U. 

Ulna,  [(olsvrj,  the  cubit),  one  of  the  bones  of  the  fore-arm. 
Umbilicus,  [ofiefokog),  the  navel. 

Urachus,  (ovgoy,  urine,  and  ;(Sijd,  to  pour),  a ligament  of  the  bladder, 
occupying  the  place  of  the  urinary  passage  of  the  foetal  quad- 
ruped, which  goes  into  the  allantois. 


336 


GLOSSARY. 


Ureter,  {ovqov,  urine),  the  canal  that  transmits  the  urine  from  the 
kidney  into  the  bladder. 

Urethra.,  (ovQijd^a),  the  canal  through  which  urine  passes  from  the 
bladder. 

Uterus,  [vgre^a,  matrix),  the  womb. 

Uvea,  (uva,  a grape),  the  posterior  lamina  of  the  iris. 

Uvula,  the  pendulous  body  which  hangs  down  from  the  middle  of 
the  soft  palate. 

V. 

Valves,  faaZz)(E,  folding  doors),  little  membranes  preventing  the  re- 
turn of  the  fluids  in  the  bloodvessels  and  absorbents. 

Ventricle,  (venter,  the  stomach),  applied  in  anatomy  to  the  cavities 
of  the  brain  and  heart. 

Vertebrje,  (verto,  to  turn),  the  bones  of  the  spine. 

Vesicle,  (vesiea,  bladder),  a small  bladder-like  cavity. 

Vomer,  (a  ploughshare),  a bone  of  the  nose. 


X. 

Xiphoid,  {^lepog,  a sword,)  like  a sword,  a term  applied  to  the  carti- 
lage of  the  sternum. 

Z. 

Zygoma,  (‘i^vyog,  a yoke),  the  arch  formed  by  the  zygomatic  processes 
of  the  temporal  and  cheek  bones. 


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